Mask configured to maintain nutrient transport without producing visible diffraction patterns

ABSTRACT

A mask configured to be implanted in a cornea of a patient to increase the depth of focus of the patient includes an anterior surface, a posterior surface, and a plurality of holes. The anterior surface is configured to reside adjacent a first corneal layer. The posterior surface is configured to reside adjacent a second corneal layer. The plurality of holes extends at least partially between the anterior surface and the posterior surface. The holes of the plurality of holes are configured to substantially eliminate visible diffraction patterns.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/854,033, filed May 26, 2004, which claims priority under 35 U.S.C.§119(e) to U.S. Provisional Application No. 60/473,824, filed on May 28,2003 and to U.S. Provisional Application No. 60/479,129, filed on Jun.17, 2003, all of which are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This application is directed to masks for improving the depth of focusof an eye of a human patient and methods and apparatuses for applyingsuch masks. More particularly, this application is directed toapparatuses and methods for aligning a mask with the line of sight of aneye and applying the mask to the eye.

2. Description of the Related Art

Presbyopia, or the inability to clearly see objects up close is a commoncondition that afflicts many adults over the age of 40. Presbyopiadiminishes the ability to see or read up close. Near objects appearblurry and out of focus. Presbyopia may be caused by defects in thefocusing elements of the eye or the inability (due to aging) of theciliary muscles to contract and relax and thereby control the shape ofthe lens in the eye.

The human eye functions by receiving light rays from an object andbending, refracting, and focusing those rays. The primary focusingelements of the human eye are the lens (also referred to as theintraocular lens) and the cornea. Light rays from an object are bent bythe cornea, which is located in the anterior part of the eye. The lightrays subsequently pass through the intraocular lens and are focusedthereby onto the retina, which is the primary light receiving element ofthe eye. From the retina, the light rays are converted to electricalimpulses, which are then transmitted by the optic nerves to the brain.

Ideally, the cornea and lens bend and focus the light rays in such a waythat they converge at a single point on the retina. Convergence of thelight rays on the retina produces a focused image. However, if thecornea or the lens are not functioning properly, or are irregularlyshaped, the images may not converge at a single point on the retina.Similarly, the image may not converge at a single point on the retina ifthe muscles in the eye can no longer adequately control the lens. Thiscondition is sometimes described as loss of accommodation. In presbyopicpatients, for example, the light rays often converge at a point behindthe retina. To the patient, the resulting image is out of focus andappears blurry.

Traditionally, vision improvement has been achieved by prescribing eyeglasses or contact lenses to the patient. Eye glasses and contact lensesare shaped and curved to help bend light rays and improve focusing ofthe light rays onto the retina of the patient. However, some visiondeficiencies, such as presbyopia, are not adequately addressed by theseapproaches.

SUMMARY OF THE INVENTION

In one embodiment, a mask configured to be implanted in a cornea of apatient to increase the depth of focus of the patient includes ananterior surface, a posterior surface, and a plurality of holes. Theanterior surface is configured to reside adjacent a first corneal layer.The posterior surface is configured to reside adjacent a second corneallayer. The plurality of holes extends at least partially between theanterior surface and the posterior surface. The plurality of holes isconfigured to substantially eliminate visible diffraction patterns.

In another embodiment, a mask configured to be implanted in a cornea ofa patient to increase the depth of focus of the patient is provided. Themask includes a body that has an anterior surface configured to resideadjacent a first corneal layer and a posterior surface configured toreside adjacent a second corneal layer. The body is formed of asubstantially opaque material that has a relatively high water content.The body is capable of substantially maintaining natural nutrient flowfrom the first corneal layer to the second corneal layer. The body beingis configured to substantially eliminate diffraction patterns that arevisible to the patient.

In another embodiment, a method of making a mask is provided. A body isconfigured to have an anterior surface capable of residing adjacent afirst layer of a cornea of a patient and a posterior surface capable ofresiding adjacent a second layer of the cornea. A peripheral portion ofthe body is configured to be substantially opaque to incident light. Acentral portion of the body is configured to be transparent along anoptic axis to substantially all of the incident light. The body isconfigured with a transport structure capable of substantiallymaintaining natural nutrient flow from the first layer to the secondlayer without producing visible diffraction patterns.

In another embodiment, a method of making a mask is provided. A bodythat has an anterior surface, a posterior surface, an outer periphery,and an inner periphery is provided. The anterior surface is configuredto reside adjacent a first layer of a cornea of a patient. The posteriorsurface is configured to reside adjacent a second layer of the cornea. Aplurality of non-uniform locations for forming a plurality of holesbetween the anterior surface and the posterior surface is generated. Asubset of locations among the plurality of locations is modified tomaintain a performance characteristic of the mask. A hole is formed inthe body at locations corresponding to the subset of locations. Theholes are configured to substantially maintain natural nutrient flowfrom the first layer to the second layer without producing visiblediffraction patterns.

In one embodiment, a method is provided for increasing the depth offocus of an eye of a patient. The eye has a visual axis. The visual axisof the eye is aligned with an instrument axis of an ophthalmicinstrument. The ophthalmic instrument has an aperture through which thepatient may look along the instrument axis. A first reference target isimaged on the instrument axis at a first distance with respect to theeye. A second reference target is imaged on the instrument axis at asecond distance with respect to the eye. The second distance is greaterthan the first distance. Movement is provided such that the patient'seye is in a position where the images of the first and second referencetargets appear to the patient's eye to be aligned. A mask comprising apin-hole aperture having a mask axis is aligned with the instrument axissuch that the mask axis and the instrument axis are substantiallycollinear. The mask is applied to the eye of the patient while thealignment of the mask and the instrument axis is maintained.

In another embodiment, a method for increasing the depth of focus of aneye of a patient is provided. The eye includes a visual axis and acornea that has an epithelial sheet, a Bowman's membrane, and a stroma.The visual axis of the eye is located using more than one referencetarget. A mask that includes a pin-hole aperture having a mask axis isaligned with the visual axis of the eye. The mask is applied to the eyewhile maintaining the alignment of the mask axis and the visual axis.

In another embodiment, a method for correcting vision is provided. ALASIK procedure is performed. The eye is moved until at least tworeference targets are aligned. A mask is applied to the eye.

In another embodiment, an apparatus for aligning a mask with a visualaxis of an eye of a patient includes an optics housing, a first target,a second target, a lens, and a light source. The optics housing definesan aperture at a first location into which the eye may be directed andan instrument axis. The first target is coupled with the optics housingand is positioned on the instrument axis at a first distance relative tothe first location. The second target is coupled with the optics housingand is positioned on the instrument axis at a second distance relativeto the first location. The lens is coupled with the optics housing. Thesecond distance is equal to the focal length of the lens. The lightsource is off-set from the instrument axis and is configured to indicatethe location of the visual axis of the eye.

In another embodiment, an apparatus for aligning a mask with a visualaxis of an eye of a patient includes a fixture for locating the eye at afirst location. The apparatus for aligning also includes a first target,a second target, and a marker. The first target is positioned on aninstrument axis at a first distance relative to the first location. Thesecond target is positioned on the instrument axis at a second distancerelative to the first location. The marker is configured to indicate thelocation of the instrument axis.

In another embodiment, a method of treating a patient is provided. Areference point on a cornea is identified. The reference point ismarked. A corneal flap is lifted to expose an intracorneal surface. Animplant is positioned on the intracorneal surface. The flap is closed tocover at least a portion of the implant.

In another embodiment, a method of treating a patient is provided. Areference point on a cornea is identified. The reference point ismarked. A corneal pocket is created to expose an intracorneal surface.An implant is positioned on the intracorneal surface.

In another embodiment, a method of treating a patient is provided. Areference point on a cornea is identified. The reference point ismarked. A stromal surface is exposed. An implant is positioned on thestromal surface. At least a portion of the implant is covered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the human eye.

FIG. 2 is a cross-sectional side view of the human eye.

FIG. 3 is a cross-sectional side view of the human eye of a presbyopicpatient wherein the light rays converge at a point behind the retina ofthe eye.

FIG. 4 is a cross-sectional side view of a presbyopic eye implanted withone embodiment of a mask wherein the light rays converge at a point onthe retina.

FIG. 5 is a plan view of the human eye with a mask applied thereto.

FIG. 6 is a perspective view of one embodiment of a mask.

FIG. 7 is a plan frontal view of an embodiment of a mask with ahexagon-shaped pinhole like aperture.

FIG. 8 is a plan frontal view of an embodiment of a mask with anoctagon-shaped pinhole like aperture.

FIG. 9 is a frontal plan view of an embodiment of a mask with anoval-shaped pinhole like aperture.

FIG. 10 is a frontal plan view of an embodiment of a mask with a pointedoval-shaped pinhole like aperture.

FIG. 11 is a frontal plan view of an embodiment of a mask with astar-shaped pinhole like aperture.

FIG. 12 is a frontal plan view of an embodiment of a mask with ateardrop-shaped pinhole like aperture spaced above the true center ofthe mask.

FIG. 13 is a frontal plan view of an embodiment of a mask with ateardrop-shaped pinhole like aperture centered within the mask.

FIG. 14 is a frontal plan view of an embodiment of a mask with ateardrop-shaped pinhole like aperture spaced below the true center ofthe mask.

FIG. 15 is a frontal plan view of an embodiment of a mask embodying witha square-shaped pinhole like aperture.

FIG. 16 is a frontal plan view of an embodiment of a mask with akidney-shaped oval pinhole like aperture.

FIG. 17 is a side view of an embodiment of a convex mask.

FIG. 18 is a side view of an embodiment of a concave mask.

FIG. 19 is a side view of an embodiment of a mask with a gel to provideopacity to the lens.

FIG. 20 is frontal plan view of an embodiment of a mask with a weave ofpolymeric fibers.

FIG. 21 is a side view of the mask of FIG. 20.

FIG. 22 is a front plan view of an embodiment of a mask having regionsof varying opacity.

FIG. 23 is a side view of the mask of FIG. 22.

FIG. 24 is a frontal plan view of an embodiment of a mask that includesa centrally located pinhole like aperture and radially extending slotsemanating from the center to the periphery of the mask.

FIG. 25 is a side view of the mask of FIG. 24.

FIG. 26 is a frontal plan view of an embodiment of a mask that includesa central pinhole like aperture, surrounded by a plurality of holesradially spaced from the pinhole like aperture and slots extendingradially spaced from the holes and extending to the periphery of themask.

FIG. 27 is a side view of the mask of FIG. 26.

FIG. 28 is a frontal plan view of an embodiment of a mask that includesa central pinhole like aperture, a region that includes a plurality ofholes radially spaced from the aperture, and a region that includesrectangular slots spaced radially from the holes.

FIG. 29 is a side view of the mask of FIG. 28.

FIG. 30 is a frontal plan view of an embodiment of a mask that includesa non-circular pinhole like aperture, a first set of slots radiallyspaced from the aperture, and a region that includes a second set ofslots extending to the periphery of the mask and radially spaced fromthe first set of slots.

FIG. 31 is a side view of the mask of FIG. 30.

FIG. 32 is a frontal plan view of an embodiment of a mask that includesa central pinhole like aperture and a plurality of holes radially spacedfrom the aperture.

FIG. 33 is a side view of the mask of FIG. 32.

FIG. 34 is an embodiment of a mask that includes two semi-circular maskportions.

FIG. 35 is an embodiment of a mask that includes a half-moon shapedregion and a centrally-located pinhole like aperture.

FIG. 36 is an embodiment of a mask including two half-moon shapedportions.

FIG. 37 is a enlarged, diagrammatic view of an embodiment of a mask thatincludes particulate structure adapted for selectively controlling lighttransmission through the mask in a high light environment.

FIG. 38 is a view of the mask of FIG. 37 in a low light environment.

FIG. 39 is an embodiment of a mask that includes a barcode formed on theannular region of the mask.

FIG. 40 is another an embodiment of a mask that includes connectors forsecuring the mask within the eye.

FIG. 41 is a plan view of an embodiment of a mask made of a spiraledfibrous strand.

FIG. 42 is a plan view of the mask of FIG. 41 being removed from theeye.

FIG. 43 is a cross-sectional view similar to that of FIG. 1, but showingcertain axes of the eye.

FIG. 44A illustrates a single-target fixation method for aligning an eyewith the optical axis of an ophthalmic instrument.

FIG. 44B illustrates another single-target fixation method for aligningan eye with the optical axis of an ophthalmic instrument.

FIG. 45A shows an apparatus for projecting a target onto an optical axisat an infinite distance.

FIG. 45B shows an apparatus for projecting a target onto an optical axisat a finite distance.

FIG. 46 illustrates a dual-target fixation method.

FIG. 47 shows an apparatus with which two targets can be projectedsimultaneously by the same projection lens to provide fixation targetsat a large distance (such as infinity) and a shorter (finite) distance.

FIG. 48 shows another embodiment of an apparatus for combining twotargets to project them simultaneously at different axial distances.

FIG. 49A shows an example of a dual target pattern as viewed by thepatient when the target patterns are aligned.

FIG. 49B shows the dual target pattern of FIG. 49A when the patterns areoffset.

FIG. 50A shows an example of another dual target pattern as viewed bythe patient when the target patterns are aligned.

FIG. 50B shows the dual target pattern of FIG. 50A when the targetpatterns are offset.

FIG. 51 shows one embodiment of an apparatus configured to locate thevisual axis of an eye of a patient by aligning the axis with an axis ofthe apparatus.

FIG. 52 is a flow chart illustrating one method of screening a patientfor the use of a mask.

FIG. 53A-53C show a mask, similar to those described herein, insertedbeneath an epithelium sheet of a cornea.

FIG. 54A-54C show a mask, similar to those described herein, insertedbeneath an Bowman's membrane of a cornea.

FIG. 55 is a schematic diagram of one embodiment of a surgical systemconfigured located the visual axis of a patient's eye by aligning thevisual axis with an axis of the system.

FIG. 55A is a perspective view of another embodiment of a dual targetfixation target.

FIG. 55B is a top view of the fixation target of FIG. 55A showing thefirst target.

FIG. 55C is a top view of the fixation target of FIG. 55A showing thesecond target.

FIG. 56 is a top view of another embodiment of a surgical system thatincludes an alignment device and a clamp configured to couple thealignment device with a surgical viewing device.

FIG. 57 is a perspective view of the alignment device shown in FIG. 56.

FIG. 58 is a top view of the alignment device shown in FIG. 57.

FIG. 59 is a schematic view of internal components of the alignmentdevice of FIG. 57.

FIG. 60 is a top view of another embodiment of a mask configured toincrease depth of focus.

FIG. 60A is an enlarged view of a portion of the view of FIG. 60.

FIG. 61A is a cross-sectional view of the mask of FIG. 60A taken alongthe section plane 61-61.

FIG. 61B is a cross-sectional view similar to FIG. 61A of anotherembodiment of a mask.

FIG. 61C is a cross-sectional view similar to FIG. 61C of anotherembodiment of a mask.

FIG. 62A is a graphical representation of one arrangement of holes of aplurality of holes that may be formed on the mask of FIG. 60.

FIG. 62B is a graphical representation of another arrangement of holesof a plurality of holes that may be formed on the mask of FIG. 60.

FIG. 62C is a graphical representation of another arrangement of holesof a plurality of holes that may be formed on the mask of FIG. 60.

FIG. 63A is an enlarged view similar to that of FIG. 60A showing avariation of a mask having non-uniform size.

FIG. 63B is an enlarged view similar to that of FIG. 60A showing avariation of a mask having a non-uniform facet orientation.

FIG. 64 is a top view of another embodiment of a mask having a holeregion and a peripheral region.

FIG. 65 is a cross-sectional view of an eye illustrating a treatment ofa patient wherein a flap is opened to place an implant and a location ismarked for placement of the implant.

FIG. 65A is a partial plan view of the eye of FIG. 65 wherein an implanthas been applied to a corneal flap and positioned with respect to aring.

FIG. 66 is a cross-sectional view of an eye illustrating a treatment ofa patient wherein a pocket is created to place an implant and a locationis marked for placement of the implant.

FIG. 66A is a partial plan view of the eye of FIG. 66 wherein an implanthas been positioned in a pocket and positioned with respect to a ring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This application is directed to masks for improving the depth of focusof an eye of a patient and methods and apparatuses for applying suchmasks. The masks generally employ pin-hole vision correction and havenutrient transport structures. The masks may be applied to the eye inany manner and in any location, e.g., as an implant in the cornea(sometimes referred to as a “corneal inlay”). The masks can also beembodied in or combined with lenses and applied in other regions of theeye, e.g., as or in combination with a contact lenses or an intraocularlenses. Apparatuses and methods for applying the masks to the patientgenerally use the patient's vision to locate the patient's line of sightwhile the mask is being applied to the eye so that the mask may beproperly aligned with the line of sight.

I. Overview of Pin-Hole Vision Correction

A mask that has a pinhole aperture may be used to improve the depth offocus of a human eye. As discussed above, presbyopia is a problem of thehuman eye that commonly occurs in older human adults wherein the abilityto focus becomes limited to inadequate range. FIGS. 1-6 illustrate howpresbyopia interferes with the normal function of the eye and how a maskwith a pinhole aperture mitigates the problem.

FIG. 1 shows the human eye, and FIG. 2 is a side view of the eye 10. Theeye 10 includes a cornea 12 and an intraocular lens 14 posterior to thecornea 12. The cornea 12 is a first focusing element of the eye 10. Theintraocular lens 14 is a second focusing element of the eye 10. The eye10 also includes a retina 16, which lines the interior of the rearsurface of the eye 10. The retina 16 includes the receptor cells whichare primarily responsible for the sense of vision. The retina 16includes a highly sensitive region, known as the macula, where signalsare received and transmitted to the visual centers of the brain via theoptic nerve 18. The retina 16 also includes a point with particularlyhigh sensitivity 20, known as the fovea. As discussed in more detail inconnection with FIG. 8, the fovea 20 is slightly offset from the axis ofsymmetry of the eye 10.

The eye 10 also includes a ring of pigmented tissue known as the iris22. The iris 22 includes smooth muscle for controlling and regulatingthe size of an opening 24 in the iris 22, which is known as the pupil.An entrance pupil 26 is seen as the image of the iris 22 viewed throughthe cornea 12 (See FIG. 7). A central point of the entrance pupil 28 isillustrated in FIG. 7 and will be discussed further below.

The eye 10 resides in an eye-socket in the skull and is able to rotatetherein about a center of rotation 30.

FIG. 3 shows the transmission of light through the eye 10 of apresbyotic patient. Due to either an aberration in the cornea 12 or theintraocular lens 14, or loss of muscle control, light rays 32 enteringthe eye 10 and passing through the cornea 12 and the intraocular lens 14are refracted in such a way that the light rays 32 do not converge at asingle focal point on the retina 16. FIG. 3 illustrates that in apresbyotic patient, the light rays 32 often converge at a point behindthe retina 16. As a result, the patient experiences blurred vision.

Turning now to FIG. 4, there is shown the light transmission through theeye 10 to which a mask 34 has been applied. The mask 34 is shownimplanted in the cornea 12 in FIG. 4. However, as discussed below, itwill be understood that the mask 34 can be, in various modes ofapplication, implanted in the cornea 12 (as shown), used as a contactlens placed over the cornea 12, incorporated in the intraocular lens 14(including the patient's original lens or an implanted lens), orotherwise positioned on or in the eye 10. In the illustrated embodiment,the light rays 32 that pass through the mask 34, the cornea 12, and thelens 14 converge at a single focal point on the retina 16. The lightrays 32 that would not converge at the single point on retina 16 areblocked by the mask 34. As discussed below, it is desirable to positionthe mask 34 on the eye 10 so that the light rays 32 that pass throughthe mask 34 converge at the fovea 20.

Turning now to FIG. 6, there is shown one embodiment of the mask 34. Asseen, the mask 34 preferably includes an annular region 36 surrounding apinhole opening or aperture 38 substantially centrally located on themask 34. The pinhole aperture 38 is generally located around a centralaxis 39, referred to herein as the optical axis of the mask 34. Thepinhole aperture 38 preferably is in the shape of a circle. It has beenreported that a circular aperture, such as the aperture 38 may, in somepatients, produce a so-called “halo effect” where the patient perceivesa shimmering image around the object being viewed. Accordingly, it maybe desirable to provide an aperture 38 in a shape that diminishes,reduces, or completely eliminates the so-called “halo effect.”

II. Masks Employing Pin-Hole Correction

FIGS. 7-42 illustrate a variety of embodiments of masks that can improvethe vision of a patient with presbyopia. The masks described inconnection with FIG. 7-42 are similar to the mask 34, except as setforth below. Accordingly, the masks described in connection with FIGS.7-42 can be used and applied to the eye 10 of a patient in a similarfashion to the mask 34. For example, FIG. 7 shows an embodiment of amask 34 a that includes an aperture 38 a formed in the shape of ahexagon. FIG. 8 shows another embodiment of a mask 34 b that includes anaperture 38 b formed in the shape of an octagon. FIG. 9 shows anotherembodiment of a mask 34 c that includes an aperture 38 c formed in theshape of an oval, while FIG. 10 shows another embodiment of a mask 34 dthat includes an aperture 38 d formed in the shape of a pointed oval.FIG. 11 shows another embodiment of a mask 34 e wherein the aperture 38e is formed in the shape of a star or starburst.

FIGS. 12-14 illustrate further embodiments that have tear-drop shapedapertures. FIG. 12 shows a mask 34 f that has a tear-drop shapedaperture 38 f that is located above the true center of the mask 34 f.FIG. 13 shows a mask 34 g that has a tear-drop shaped aperture 38 g thatis substantially centered in the mask 34 g. FIG. 14 shows a mask 34 hthat has a tear-drop shaped aperture 38 h that is below the true centerof the mask 34 h. FIG. 12-14 illustrate that the position of aperturecan be tailored, e.g., centered or off-center, to provide differenteffects. For example, an aperture that is located below the true centerof a mask generally will allow more light to enter the eye because theupper portion of the aperture 34 will not be covered by the eyelid ofthe patient. Conversely, where the aperture is located above the truecenter of the mask, the aperture may be partially covered by the eyelid.Thus, the above-center aperture may permit less light to enter the eye.

FIG. 15 shows an embodiment of a mask 34 i that includes an aperture 38i formed in the shape of a square. FIG. 16 shows an embodiment of a mask34 j that has a kidney-shaped aperture 38 j. It will be appreciated thatthe apertures shown in FIGS. 7-16 are merely exemplary of non-circularapertures. Other shapes and arrangements may also be provided and arewithin the scope of the present invention.

The mask 34 preferably has a constant thickness, as discussed below.However, in some embodiments, the thickness of the mask may vary betweenthe inner periphery (near the aperture 38) and the outer periphery. FIG.17 shows a mask 34 k that has a convex profile, i.e., that has agradually decreasing thickness from the inner periphery to the outerperiphery. FIG. 18 shows a mask 34 l that has a concave profile, i.e.,that has a gradually increasing thickness from the inner periphery tothe outer periphery. Other cross-sectional profiles are also possible.

The annular region 36 is at least partially and preferably completelyopaque. The opacity of the annular region 36 prevents light from beingtransmitted through the mask 32 (as generally shown in FIG. 4). Opacityof the annular region 36 may be achieved in any of several differentways.

For example, in one embodiment, the material used to make mask 34 may benaturally opaque. Alternatively, the material used to make the mask 34may be substantially clear, but treated with a dye or other pigmentationagent to render region 36 substantially or completely opaque. In stillanother example, the surface of the mask 34 may be treated physically orchemically (such as by etching) to alter the refractive and transmissiveproperties of the mask 34 and make it less transmissive to light.

In still another alternative, the surface of the mask 34 may be treatedwith a particulate deposited thereon. For example, the surface of themask 34 may be deposited with particulate of titanium, gold or carbon toprovide opacity to the surface of the mask 34. In another alternative,the particulate may be encapsulated within the interior of the mask 34,as generally shown in FIG. 19. Finally, the mask 34 may be patterned toprovide areas of varying light transmissivity, as generally shown inFIGS. 24-33, which are discussed in detail below.

Turning to FIG. 20, there is shown a mask 34 m formed or made of a wovenfabric, such as a mesh of polyester fibers. The mesh may be across-hatched mesh of fibers. The mask 34 m includes an annular region36 m surrounding an aperture 38 m. The annular region 36 m comprises aplurality of generally regularly positioned apertures 36 m in the wovenfabric allow some light to pass through the mask 34 m. The amount oflight transmitted can be varied and controlled by, for example, movingthe fibers closer together or farther apart, as desired. Fibers moredensely distributed allow less light to pass through the annular region36 m. Alternatively, the thickness of fibers can be varied to allow moreor less light through the openings of the mesh. Making the fiber strandslarger results in the openings being smaller.

FIG. 22 shows an embodiment of a mask 34 n that includes an annularregion 36 n that has sub-regions with different opacities. The opacityof the annular region 36 n may gradually and progressively increase ordecrease, as desired. FIG. 22 shows one embodiment where a first area 42closest to an aperture 38 n has an opacity of approximately 60%. In thisembodiment, a second area 44, which is outlying with respect to thefirst area 42, has a greater opacity, such as 70%. In this embodiment, athird area 46, which is outlying with respect to the second area 42, hasan opacity of between 85 to 100%. The graduated opacity of the typedescribed above and shown in FIG. 22 is achieved in one embodiment by,for example, providing different degrees of pigmentation to the areas42, 44 and 46 of the mask 34 n. In another embodiment, light blockingmaterials of the type described above in variable degrees may beselectively deposited on the surface of a mask to achieve a graduatedopacity.

In another embodiment, the mask may be formed from co-extruded rods madeof material having different light transmissive properties. Theco-extruded rod may then be sliced to provide disks for a plurality ofmasks, such as those described herein.

FIGS. 24-33 shows examples of masks that have been modified to provideregions of differing opacity. For example, FIG. 24 shows a mask 34 othat includes an aperture 38 o and a plurality of cutouts 48 in thepattern of radial spokes extending from near the aperture 38 o to anouter periphery 50 of the mask 34 o. FIG. 24 shows that the cutouts 48are much more densely distributed about a circumference of the mask nearaperture 38 o than are the cutouts 48 about a circumference of the masknear the outer periphery 50. Accordingly, more light passes through themask 34 o nearer aperture 38 o than near the periphery 50. The change inlight transmission through the mask 34 o is gradual.

FIGS. 26-27 show another embodiment of a mask 34 p. The mask 34 pincludes an aperture 38 p and a plurality of circular cutouts 52 p, anda plurality of cutouts 54 p. The circular cutouts 52 p are locatedproximate the aperture 38 p. The cutouts 54 p are located between thecircular cutouts 52 p and the periphery 50 p. The density of thecircular cutouts 52 p generally decreases from the near the aperture 38p toward the periphery 50 p. The periphery 50 p of the mask 34 p isscalloped by the presence of the cutouts 54, which extend inward fromthe periphery 50 p, to allow some light to pass through the mask at theperiphery 50 p.

FIGS. 28-29 shows another embodiment similar to that of FIGS. 26-27wherein a mask 34 q includes a plurality of circular cutouts 52 q and aplurality of cutouts 54 q. The cutouts 54 q are disposed along theoutside periphery 50 q of the mask 34 q, but not so as to provide ascalloped periphery.

FIGS. 30 and 31 illustrate an embodiment of a mask 34 r that includes anannular region 36 r that is patterned and an aperture 38 r that isnon-circular. As shown in FIG. 30, the aperture 38 r is in the shape ofa starburst. Surrounding the aperture 38 r is a series of cutouts 54 rthat are more densely spaced toward the aperture 38 r. The mask 34 rincludes an outer periphery 50 r that is scalloped to provide additionallight transmission at the outer periphery 50 r.

FIGS. 32 and 33 show another embodiment of a mask 34 s that includes anannular region 36 s and an aperture 38 s. The annular region 36 s islocated between an outer periphery 50 s of the mask 34 s and theaperture 38 s. The annular region 36 s is patterned. In particular, aplurality of circular openings 56 s is distributed over the annularregion 36 s of the mask 34 s. It will be appreciated that the density ofthe openings 56 s is greater near the aperture 38 s than near theperiphery 50 s of the mask 34 s. As with the examples described above,this results in a gradual increase in the opacity of the mask 34 s fromaperture 38 s to periphery 50 s.

FIGS. 34-36 show further embodiments. In particular, FIG. 34 shows amask 34 t that includes a first mask portion 58 t and a second maskportion 60 t. The mask portions 58 t, 60 t are generally “C-shaped.” Asshown in FIG. 34, the mask portions 58 t, 60 t are implanted or insertedsuch that the mask portions 58 t, 60 t define a pinhole or aperture 38t.

FIG. 35 shows another embodiment wherein a mask 34 u includes two maskportions 58 u, 60 u. Each mask portion 58 u, 60 u is in the shape of ahalf-moon and is configured to be implanted or inserted in such a waythat the two halves define a central gap or opening 62 u, which permitslight to pass therethrough. Although opening 62 u is not a circularpinhole, the mask portions 58 u, 60 u in combination with the eyelid(shown as dashed line 64) of the patient provide a comparable pinholeeffect.

FIG. 36 shows another embodiment of a mask 34 v that includes anaperture 38 v and that is in the shape of a half-moon. As discussed inmore detail below, the mask 34 v may be implanted or inserted into alower portion of the cornea 12 where, as described above, thecombination of the mask 34 v and the eyelid 62 provides the pinholeeffect.

Other embodiments employ different ways of controlling the lighttransmissivity through a mask. For example, the mask may be a gel-filleddisk, as shown in FIG. 19. The gel may be a hydrogel or collagen, orother suitable material that is biocompatible with the mask material andcan be introduced into the interior of the mask. The gel within the maskmay include particulate 66 suspended within the gel. Examples ofsuitable particulate are gold, titanium, and carbon particulate, which,as discussed above, may alternatively be deposited on the surface of themask.

The material of the mask 34 may be any biocompatible polymeric material.Where a gel is used, the material is suitable for holding a gel.Examples of suitable materials for the mask 34 include the preferredpolymethylmethacrylate or other suitable polymers, such aspolycarbonates and the like. Of course, as indicated above, fornon-gel-filled materials, a preferred material may be a fibrousmaterial, such as a Dacron mesh.

The mask 34 may also be made to include a medicinal fluid, such as anantibiotic that can be selectively released after application,insertion, or implantation of the mask 34 into the eye of the patient.Release of an antibiotic after application, insertion, or implantationprovides faster healing of the incision. The mask 34 may also be coatedwith other desired drugs or antibiotics. For example, it is known thatcholesterol deposits can build up on the eye. Accordingly, the mask 34may be provided with a releasable cholesterol deterring drug. The drugmay be coated on the surface of the mask 34 or, in an alternativeembodiment, incorporated into the polymeric material (such as PMMA) fromwhich the mask 34 is formed.

FIGS. 37 and 38 illustrate one embodiment where a mask 34 w comprises aplurality of nanites 68. “Nanites” are small particulate structures thathave been adapted to selectively transmit or block light entering theeye of the patient. The particles may be of a very small size typical ofthe particles used in nanotechnology applications. The nanites 68 aresuspended in the gel or otherwise inserted into the interior of the mask34 w, as generally shown in FIGS. 37 and 38. The nanites 68 can bepreprogrammed to respond to different light environments.

Thus, as shown in FIG. 37, in a high light environment, the nanites 68turn and position themselves to substantially and selectively block someof the light from entering the eye. However, in a low light environmentwhere it is desirable for more light to enter the eye, nanites mayrespond by turning or be otherwise positioned to allow more light toenter the eye, as shown in FIG. 38.

Nano-devices or nanites are crystalline structures grown inlaboratories. The nanites may be treated such that they are receptive todifferent stimuli such as light. In accordance with one aspect of thepresent invention, the nanites can be imparted with energy where, inresponse to a low light and high light environments, they rotate in themanner described above and generally shown in FIG. 38.

Nanoscale devices and systems and their fabrication are described inSmith et al., “Nanofabrication,” Physics Today, February 1990, pp. 24-30and in Craighead, “Nanoelectromechanical Systems,” Science, Nov. 24,2000, Vol. 290, pp. 1532-1535, both of which are incorporated byreference herein in their entirety. Tailoring the properties ofsmall-sized particles for optical applications is disclosed in Chen etal. “Diffractive Phase Elements Based on Two-Dimensional ArtificialDielectrics,” Optics Letters, Jan. 15, 1995, Vol. 20, No. 2, pp.121-123, also incorporated by reference herein in its entirety.

Masks 34 made in accordance with the present invention may be furthermodified to include other properties. FIG. 39 shows one embodiment of amask 34 x that includes a bar code 70 or other printed indicia.

The masks described herein may be incorporated into the eye of a patientin different ways. For example, as discussed in more detail below inconnection with FIG. 52, the mask 34 may be provided as a contact lensplaced on the surface of the eyeball 10. Alternatively, the mask 34 maybe incorporated in an artificial intraocular lens designed to replacethe original lens 14 of the patient. Preferably, however, the mask 34 isprovided as a corneal implant or inlay, where it is physically insertedbetween the layers of the cornea 12.

When used as a corneal implant, layers of the cornea 12 are peeled awayto allow insertion of the mask 34. Typically, the optical surgeon (usinga laser) cuts away and peels away a flap of the overlying cornealepithelium. The mask 34 is then inserted and the flap is placed back inits original position where, over time, it grows back and seals theeyeball. In some embodiments, the mask 34 is attached or fixed to theeye 10 by support strands 72 and 74 shown in FIG. 40 and generallydescribed in U.S. Pat. No. 4,976,732, incorporated by reference hereinin its entirety.

In certain circumstances, to accommodate the mask 34, the surgeon may berequired to remove additional corneal tissue. Thus, in one embodiment,the surgeon may use a laser to peel away additional layers of the cornea12 to provide a pocket that will accommodate the mask 34. Application ofthe mask 34 to the cornea 12 of the eye 10 of a patient is described ingreater detail in connection with FIGS. 53A-54C.

Removal of the mask 34 may be achieved by simply making an additionalincision in the cornea 12, lifting the flap and removing the mask 34.Alternatively, ablation techniques may be used to completely remove themask 34.

FIGS. 41 and 42 illustrate another embodiment, of a mask 34 y thatincludes a coiled strand 80 of a fibrous or other material. Strand 80 iscoiled over itself to form the mask 34 y, which may therefore bedescribed as a spiral-like mask. This arrangement provides a pinhole oraperture 38 y substantially in the center of the mask 34 y. The mask 34y can be removed by a technician or surgeon who grasps the strand 80with tweezers 82 through an opening made in a flap of the corneal 12.FIG. 42 shows this removal technique.

Further mask details are disclosed in U.S. Pat. No. 4,976,732, issuedDec. 11, 1990 and in U.S. Provisional Application Ser. No. 60/473,824,filed May 28, 2003, both of which are incorporated by reference hereinin their entirety.

III. Methods of Applying Pinhole Aperture Devices

The various masks discussed herein can be used to improve the vision ofa presbyopic patient as well as patient's with other vision problems.The masks discussed herein can be deployed in combination with a LASIKprocedure, to eliminate the effects of abrasions, aberrations, anddivots in the cornea. It is also believed that the masks disclosedherein can be used to treat patients suffering from maculardegeneration, e.g., by directing light rays to unaffected portions ofretina, thereby improving the vision of the patient. Whatever treatmentis contemplated, more precise the alignment of the central region of amask with a pin-hole aperture with the visual axis of the patient isbelieved to provide greater clinical effect to the patient.

A. Alignment of the Pinhole Aperture with the Patient's Visual Axis

Alignment of the central region of the pinhole aperture 38, inparticular, the optical axis 39, of the mask 34 with the visual axis ofthe eye 10 may be achieved in a variety of ways. As discussed more fullybelow, such alignment may be achieved by imaging two reference targetsat different distances and effecting movement of the patient's eye to aposition where the images of the first and second reference targetsappear aligned as viewed by the patient's eye. When the patient viewsthe targets as being aligned, the patient's visual axis is located.

FIG. 43 is a cross-sectional view of the eye 10, similar to that shownin FIG. 1, indicating a first axis 1000 and a second axis 1004. Thefirst axis 1000 represents the visual axis, or line of sight, of thepatient and the second axis 1004 indicates the axis of symmetry of theeye 10. The visual axis 1000 is an axis that connects the fovea 20 and atarget 1008. The visual axis 1000 also extends through the central point28 of the entrance pupil 26. The target 1008 is sometimes referred toherein as a “fixation point.” The visual axis 1000 also corresponds tothe chief ray of the bundle of rays emanating from the target 1008 thatpasses through the pupil 22 and reaches the fovea 20. The axis ofsymmetry 1004 is an axis passing through the central point 28 of theentrance pupil 26 and the center of rotation 30 of the eye 10. Asdescribed above, the cornea 12 is located at the front of the eye 10and, along with the iris 22, admits light into the eye 10. Lightentering the eye 10 is focused by the combined imaging properties of thecornea 12 and the intraocular lens 14 (see FIGS. 2-3).

In a normal eye, the image of the target 1008 is formed at the retina16. The fovea 20 (the region of the retina 16 with particularly highresolution) is slightly off-set from the axis of symmetry 1004 of theeye 10. This visual axis 1000 is typically inclined at an angle θ ofabout six (6) degrees to the axis of symmetry 1004 of the eye 10 for aneye with a centered iris.

FIGS. 44A and 44B illustrate single-target fixation methods for aligningan eye with an optical axis of an instrument also referred to herein asan “instrument axis.” In FIG. 44A, the eye 10 is shown looking into anaperture of a projection lens 1012. The lens aperture is shown as theentire lens 1012. The projection lens 1012 reimages a reference target1016 at an infinite distance, producing a collimated beam 1020.

The reference target 1016 in FIG. 44A is shown reimaged at an infinitedistance, which is achieved by positioning the target object at adistance 1024 equal to the focal length f of the lens 1012, i.e. thereference target 1016 is at the lens focal point. To first-orderapproximation, the relationship between the object and the imagedistances for a lens of focal length f follows the Gaussian equation(1/A)=(1/f)+(1/B) where B and A are respectively the object and imagedistances measured from the lens center. Because the illuminated targetappears at an infinite distance as viewed by the eye 10, individuallight rays 1020 a to 1020 g are parallel to each other.

FIG. 44A shows the eye 10 fixated on the reference target 1016 along aray 1020 c, which appears to come from the reference target 1016 asimaged by the projection lens 1012. The eye 10 is here decentered adistance 1028 from an optical axis 1032 of the instrument, i.e., theinstrument axis, which may be the central axis of the lens 1012. Thisdecentration of the eye 10 with respect to the optical axis 1032 of theinstrument does not affect fixation to an infinitely distant imagebecause all rays projected by the lens 1012 are parallel. As such, in aninstrument that relies on fixation to a single target imaged atinfinity, an eye can be fixated on the target but still be off-center ofthe optical axis of the instrument.

FIG. 44B is similar to FIG. 44A, except that a reference target 1016′ islocated somewhat closer to the projection lens 1012 that is thereference target 1016 so that an image 1036 of the reference target1016′ appears at a large but finite distance 1040 behind the lens 1012.As was the case in FIG. 44A, the eye 10 in FIG. 44B is fixated on thereference target 1016′ along a ray 1020 c′, which is decentered adistance 1028 from an optical axis 1032 of the instrument. However, therays 1020 a′ to 1020 g′ projected by the lens 1012 shown in FIG. 44B areseen to diverge as if they originated at the image 1036 of the referencetarget 1016′, which is located on the optical axis 1032 of the lens 1012at a finite distance 1040 from the lens 1012. If the decentration of theeye 10 (corresponding to the distance 1028) changes, the eye 10 mustrotate somewhat about its center of rotation 30 in order to fixate onthe image 1036. The eye 10 in FIG. 44B is shown rotated by some angle soas to align its visual axis 1000 with the direction of propagation ofray 1020 c′. Thus, in general, a decentered eye fixated on afinite-distance target is not merely off-center but is also angularlyoffset from the optical axis 1032 of the instrument.

FIG. 45A shows one embodiment of a projection lens 1012 used to createan optical image at infinite distance, as was schematically shown inFIG. 44A. The reference target 1016 typically is a back-illuminatedpattern on a transparent glass reticle 1044. The reference target 1016is located at a distance 1024 on the lens' optical axis 1032 at thelens' focal point, i.e. the reference target 1016 is located such thatthe distance 1024 is equal to the distance f. A diffusing plate 1048 anda condensing lens 1052 are used to ensure full illumination of thereference target 1016 throughout the aperture of the projection lens1012. Light rays projected by the projection lens 1012 are substantiallyparallel depending upon the degree of imaging perfection achieved in theoptical system. Assuming a well-corrected lens with small aberrations,the image as observed through the aperture of the projection lens 1012will appear to be at infinity.

FIG. 45B shows a somewhat different optical system in which a target1016′ is projected so that an image 1036 appears at a large but finitedistance 1040 behind the lens 1012, as was shown schematically in FIG.44B. The diffusing plate 1048 and the condensing lens 1052 again areused to ensure that full illumination of the target reference 112′ isachieved throughout the aperture of the projection lens 1012. In thesystem of FIG. 45B, the reference target 1016′ is located at an objectdistance 1024′, which is inside the focal point in accordance with theaforementioned Gaussian equation. Thus, the object distance 1024′ is adistance that is less than the focal length f of the lens 1012′. Thepath of a typical light ray 1056 from the center of the reference target1016′ is shown. If the eye 10 is aligned with this ray 1056, thereference target 1016 is observed as if it were located at the locationof the image 1036, i.e. at a finite distance. The ray 1056 would then besimilar to ray 1020 c′ of FIG. 44B, and fixation of the eye 10 could beestablished as appropriate for the given degree of decentration from theoptical axis 1032.

FIG. 46 illustrates a fixation method whereby the single-target fixationmethods shown in FIGS. 44A and 44B are both used simultaneously in adual-target fixation system. With two fixation targets 1016 and 1016′ atdifferent distances, the eye 10 will see angular disparity (parallax)between the target images (i.e., they will not appear to besuperimposed) if the eye is decentered. The rays 1020 a to 1020 g of theinfinite-distance target 1016 are parallel to one another, while therays 1020 a′ to 1020 g′ of the finite distance target 1016′ diverge. Theonly rays of the targets that coincide are rays 1020 d and 10204 d′,which are collinear along the optical axis 1032 of the instrument. Thus,the eye 10 can be simultaneously fixated on both targets if the visualaxis, represented by the first axis 1000 of the eye 10, is centered onthe optical axis of the instrument, i.e. along the ray 1020 d (which isthe same as 1020 d′). Thus, when the visual axis of the eye 10 lies onthe optical axis 1032 of the apparatus, both images are fixated.

FIG. 47 shows schematically an apparatus with which two reticle patternscould be projected simultaneously by the same projection lens to providefixation targets 1016 and 1016′ at a large distance 1024 (such asinfinity) and a shorter (finite) distance 1024′. It is preferable thatboth fixation targets are at relatively large distances so that onlyslight focus accommodation of the eye 10 is required to compensate forthese different distances. By instructing the patient to move his or hereye transversely with respect to the instrument axis until a visualevent occurs, e.g., angular displacement (parallax) between the imagesis minimized, alignment of the eye 10 with the optical axis 1032 of theapparatus is facilitated. Providing two fixation targets at differentapparent distances will simplify accurate alignment of the sighted eyewith an ophthalmic apparatus in the surgical procedures disclosed hereinand in other similar surgical procedures.

FIG. 48 shows another embodiment of an apparatus for combining twofixation targets 1016 and 1016′ to project them simultaneously atdifferent axial distances. A beamsplitter plate or cube 1060 is insertedbetween the patterns and the projection lens 1012 so each pattern can beilluminated independently. In the embodiments of FIGS. 46 and 47, thetargets 1016, 1016′ can be opaque lines seen against a light background,bright lines seen against a dark background, or a combination of theseforms.

FIG. 49A shows an example of a typical dual pattern as viewed by thepatient when the patterns are aligned, i.e. when the patient's eye isaligned with the optical axis of the apparatus. The dual pattern set inthis embodiment comprises an opaque fine-line cross 1064 seen against abroader bright cross 1068. FIG. 49B shows the same dual pattern set asshown in FIG. 49A, except the patterns are offset, indicating that theeye 10 is decentered with respect to the optical axis of the associatedoptical instrument.

FIG. 50A shows an example of another dual pattern as viewed by thepatient when the patterns are aligned, i.e. when the patient's eye isaligned with the optical axis of the ophthalmic instrument. The dualpattern set in this embodiment comprises an opaque circle 1072 seenagainst a bright circle 1076. The circle 1072 has a diameter that isgreater than the diameter of the circle 1076. FIG. 50B shows the samedual pattern set as shown in FIG. 50A, except the patterns are offset,indicating that the eye 10 is decentered with respect the optical axisof the associated optical instrument. It is not necessary that thetargets appear as crosses or circles; patterns such as dots, squares,and other shapes and patterns also can suffice.

In another embodiment, color is used to indicate when the patient's eyeis aligned with the optical axis of the apparatus. For example, a dualcolor set can be provided. The dual color set may comprise a firstregion of a first color and a second region of a second color. Asdiscussed above in connection with the dual pattern sets, the patientvisual axis is located when the first color and the second color are ina particular position relative to each other. This may cause a desiredvisual effect to the patient's eye, e.g., when the first region of thefirst color is aligned with the second region of the second color, thepatient may observe a region of a third color. For example, if the firstregion is colored blue and the second region is colored yellow, thepatient will see a region of green. Additional details concerninglocating a patient's visual axis or line of sight are contained in U.S.Pat. No. 5,474,548, issued Dec. 12, 1995, incorporated by referenceherein in its entirety.

FIG. 51 shows one embodiment of an ophthalmic instrument 1200 that canbe used in connection with various methods described herein to locatethe visual axis of a patient. The instrument 1200 includes an opticshousing 1202 and a patient locating fixture 1204 that is coupled withthe optics housing 1202. The optics housing 1202 includes an opticalsystem 1206 that is configured to project two reticle patternssimultaneously to provide fixation targets at a large distance, e.g.,infinity, and a shorter, finite distance.

In the illustrated embodiment, the optical system 1206 of the instrumentincludes a first reference target 1208, a second reference target 1210,and a projection lens 1212. The first and second reference targets 1208,1210 are imaged by the projection lens 1212 along an instrument axis1213 of the ophthalmic instrument 1200. In one embodiment, the firstreference target 1208 is formed on a first glass reticle 1214 located afirst distance 1216 from the lens 1212 and the second target 1210 isformed on a second glass reticle 1218 located a second distance 1220from the lens 1212. Preferably, the second distance 1220 is equal to thefocal length f of the lens 1212, as was discussed in connection withFIG. 44A. As discussed above, positioning the second target 1210 at thefocal length f of the lens 1212 causes the second target 1210 to beimaged at an infinite distance from the lens 1212. The first distance1216 preferably is less than the second distance 1220. As discussedabove, the first reference target 1208 is thereby imaged at a large butfinite distance from the lens 1212. By positioning the first and secondreference targets 1208, 1210 in this manner, the method set forth abovefor aligning the eye 10 of the patient may be implemented with theophthalmic instrument 1200.

The optical system 1206 preferably also includes a light source 1222that marks the visual axis of the patient after the visual axis has beenlocated in the manner described above. In the illustrated embodiment,the light source 1222 is positioned separately from the first and secondreference targets 1208, 1210. In one embodiment, the light source 1222is positioned at a ninety degree angle to the instrument axis 1213 andis configured to direct light toward the axis 1213. In the illustratedembodiment, a beamsplitter plate or cube 1224 is provided between thefirst and second reference targets 1208, 1210 and the patient to routelight rays emitted by the light source 1222 to the eye of the patient.The beamsplitter 1224 is an optical component that reflects light raysfrom the direction of the light source 1222, but permits the light raysto pass through the beamsplitter along the instrument axis 1213. Thus,light rays form the first and second reference targets 1208, 1210 andfrom the light source 1222 may be propagated toward the eye of thepatient. Other embodiments are also possible. For example, thebeamsplitter 1224 could be replaced with a mirror that is movable intoand out of the instrument axis 1213 to alternately reflect light fromthe light source 1222 to the eye or to permit light from the first andsecond reference targets 1208, 1210 to reach the eye.

The patient locating fixture 1204 includes an elongate spacer 1232 and acontoured locating pad 1234. The contoured locating pad 1234 defines anaperture through which the patient may look along the instrument axis213. The spacer 1232 is coupled with the optics housing 1202 and extendsa distance 1236 between the housing 1202 and the contoured locating pad1234. In one embodiment, the spacer 1232 defines a lumen 1238 thatextends between the contoured locating pads 1234 and the optics housing1202. In some embodiments, the magnitude of the distance 1236 may beselected to increase the certainty of the location of the patient'svisual axis. In some embodiments, it is sufficient that the distance1236 be a relatively fixed distance.

When the alignment apparatus 1200 is used, the patient's head is broughtinto contact with the contoured locating pad 1234, which locates thepatients eye 10 in the aperture at a fixed distance from the first andsecond reference targets 1208, 1210. Once the patient's head ispositioned in the contoured locating pad 1234, the patient may move theeye 10 as discussed above, to locate the visual axis. After locating thevisual axis, the light source 1222 is engaged to emit light toward theeye 10, e.g., as reflected by the beamsplitter 1224.

In the illustrated embodiment, at least some of the light emitted by thelight source 1222 is reflected by the beamsplitter 1224 along theinstrument axis 1213 toward the patient's eye 10. Because the visualaxis of the eye 10 was previously aligned with the instrument axis 1213,the light from the light source 1222 reflected by the beamsplitter 1224is also aligned with the visual axis of the eye 10.

The reflected light provides a visual marker of the location of thepatient's visual axis. The marking function of the light source 1222 isparticularly useful in connection with the methods, described below, ofapplying a mask. Additional embodiments of ophthalmic instrumentsembodying this technique are described below in connection with FIGS.55-59.

B. Methods of Applying a Mask

Having described a method for properly locating the visual axis of theeye 10 a patient and for visually marking the visual axis, variousmethods for applying a mask to the eye will be discussed.

FIG. 52 shows an exemplary process for screening a patient interested inincreasing his or her depth of focus. The process begins at step 1300,in which the patient is fitted with soft contact lenses, i.e., a softcontact lens in placed in each of the patient's eyes. If needed, thesoft contact lenses may include vision correction. Next, at step 1310,the visual axis of each of the patient's eyes is located as describedabove. At a step 1320, a mask, such as any of those described above, isplaced on the soft contact lenses such that the optical axis of theaperture of the mask is aligned with the visual axis of the eye. In thisposition, the mask will be located generally concentric with thepatient's pupil. In addition, the curvature of the mask should parallelthe curvature of the patient's cornea. The process continues at a step1330, in which the patient is fitted with a second set of soft contactlenses, i.e., a second soft contact lens is placed over the mask in eachof the patient's eyes. The second contact lens holds the mask in asubstantially constant position. Last, at step 1340, the patient'svision is tested. During testing, it is advisable to check thepositioning of the mask to ensure that the optical axis of the apertureof the mask is substantially collinear with the visual axis of the eye.Further details of testing are set forth in U.S. Pat. No. 6,554,424,issued Apr. 29, 2003, incorporated by reference herein in its entirety.

In accordance with a still further embodiment of the invention, a maskis surgically implanted into the eye of a patient interested inincreasing his or her depth of focus. For example, a patient may sufferfrom presbyopia, as discussed above. The mask may be a mask as describedherein, similar to those described in the prior art, or a mask combiningone or more of these properties. Further, the mask may be configured tocorrect visual aberrations. To aid the surgeon surgically implanting amask into a patient's eye, the mask may be pre-rolled or folded for easeof implantation.

The mask may be implanted in several locations. For example, the maskmay be implanted underneath the cornea's epithelium sheet, beneath thecornea's Bowman membrane, in the top layer of the cornea's stroma, or inthe cornea's stroma. When the mask is placed underneath the cornea'sepithelium sheet, removal of the mask requires little more than removalof the cornea's epithelium sheet.

FIGS. 53 a through 53 c show a mask 1400 inserted underneath anepithelium sheet 1410. In this embodiment, the surgeon first removes theepithelium sheet 1410. For example, as shown in FIG. 53 a, theepithelium sheet 1410 may be rolled back. Then, as shown in FIG. 53 b,the surgeon creates a depression 1415 in a Bowman's membrane 420corresponding to the visual axis of the eye. The visual axis of the eyemay be located as described above and may be marked by use of thealignment apparatus 1200 or other similar apparatus. The depression 1415should be of sufficient depth and width to both expose the top layer1430 of the stroma 1440 and to accommodate the mask 1400. The mask 1400is then placed in the depression 1415. Because the depression 1415 islocated in a position to correspond to the visual axis of the patient'seye, the central axis of the pinhole aperture of the mask 1400 will besubstantially collinear with the visual axis of the eye. This willprovide the greatest improvement in vision possible with the mask 1400.Last, the epithelium sheet 1410 is placed over the mask 1400. Over time,as shown in FIG. 53 c, the epithelium sheet 1410 will grow and adhere tothe top layer 1430 of the stroma 1440, as well as the mask 1400depending, of course, on the composition of the mask 1400. As needed, acontact lens may be placed over the incised cornea to protect the mask.

FIGS. 54 a through 54 c show a mask 1500 inserted beneath a Bowman'smembrane 1520 of an eye. In this embodiment, as shown in FIG. 54 a, thesurgeon first hinges open the Bowman's membrane 1520. Then, as shown inFIG. 54 b, the surgeon creates a depression 1515 in a top layer 1530 ofa stroma 1540 corresponding to the visual axis of the eye. The visualaxis of the eye may be located as described above and may be marked byusing the alignment apparatus 1200 or other similar apparatus. Thedepression 1515 should be of sufficient depth and width to accommodatethe mask 1500. Then, the mask 1500 is placed in the depression 1515.Because the depression 1515 is located in a position to correspond tothe visual axis of the patient's eye, the central axis of the pinholeaperture of the mask 1500 will be substantially collinear with thevisual axis of the eye. This will provide the greatest improvement invision possible with the mask 1500. Last, the Bowman's membrane 1520 isplaced over the mask 1500. Over time, as shown in FIG. 54 c, theepithelium sheet 1510 will grow over the incised area of the Bowman'smembrane 1520. As needed, a contact lens may be placed over the incisedcornea to protect the mask.

In another embodiment, a mask of sufficient thinness, i.e., less thansubstantially 20 microns, may be placed underneath epithelium sheet1410. In another embodiment, an optic mark having a thickness less thanabout 20 microns may be placed beneath Bowman's membrane 1520 withoutcreating a depression in the top layer of the stroma.

In an alternate method for surgically implanting a mask in the eye of apatient, the mask may be threaded into a channel created in the toplayer of the stroma. In this method, a curved channeling tool creates achannel in the top layer of the stroma, the channel being in a planeparallel to the surface of the cornea. The channel is formed in aposition corresponding to the visual axis of the eye. The channelingtool either pierces the surface of the cornea or, in the alternative, isinserted via a small superficial radial incision. In the alternative, alaser focusing an ablative beam may create the channel in the top layerof the stroma. In this embodiment, the mask may be a single segment witha break, or it may be two or more segments. In any event, the mask inthis embodiment is positioned in the channel and is thereby located sothat the central axis of the pinhole aperture formed by the mask issubstantially collinear with the patient's visual axis to provide thegreatest improvement in the patient's depth of focus.

In another alternate method for surgically implanting a mask in the eyeof a patient, the mask may be injected into the top layer of the stroma.In this embodiment, an injection tool with a stop penetrates the surfaceof the cornea to the specified depth. For example, the injection toolmay be a ring of needles capable of producing a mask with a singleinjection. In the alternative, a channel may first be created in the toplayer of the stroma in a position corresponding to the visual axis ofthe patient. Then, the injector tool may inject the mask into thechannel. In this embodiment, the mask may be a pigment, or it may bepieces of pigmented material suspended in a bio-compatible medium. Thepigment material may be made of a polymer or, in the alternative, madeof a suture material. In any event, the mask injected into the channelis thereby positioned so that the central axis of the pinhole apertureformed by the pigment material is substantially collinear with thevisual axis of the patient.

In another method for surgically implanting a mask in the eye of apatient, the mask may be placed beneath the corneal flap created duringkeratectomy, when the outermost 20% of the cornea is hinged open. Aswith the implantation methods discussed above, a mask placed beneath thecorneal flap created during keratectomy should be substantially alignedwith the patient's visual axis, as discussed above, for greatest effect.

In another method for surgically implanting a mask in the eye of apatient, the mask may be aligned with the patient's visual axis andplaced in a pocket created in the cornea's stroma.

Further details concerning alignment apparatuses are disclosed in U.S.Provisional Application Ser. No. 60/479,129, filed Jun. 17, 2003,incorporated by reference herein in its entirety.

V. Further Surgical Systems for Aligning a Pinhole Aperture with aPatient's Eye

FIG. 55 shows a surgical system 2000 that employs dual target fixationin a manner similar to that discussed above in connection with FIGS.43-51. The surgical system 2000 enables the identification of a uniquefeature of a patient's eye in connection with a surgical procedure. Thesurgical system 2000 is similar to the ophthalmic instrument 1200 exceptas set forth below. As discussed below, in one arrangement, the surgicalsystem 2000 is configured to align an axis of the patient's eye, e.g.,the patient's line of sight (sometimes referred to herein as the “visualaxis”), with an axis of the system 2000. The axis of the system 2000 maybe a viewing axis along which the patient may direct an eye. Asdiscussed above, such alignment is particularly useful in many surgicalprocedures, including those that benefit from precise knowledge of thelocation of one or more structures or features of the eye on which theprocedures is being performed.

In one embodiment, the surgical system 2000 includes a surgical viewingdevice 2004 and an alignment device 2008. In one embodiment, thesurgical viewing device 2004 includes a surgical microscope. Thesurgical viewing device 2004 may be any device or combination of devicesthat enables a surgeon to visualize the surgical site with sufficientclarity or that enhances the surgeon's visualization of the surgicalsite. A surgeon also may elect to use the alignment device 2004 withouta viewing device. As discussed more fully below in connection anotherembodiment of a surgical system shown in FIG. 56, the surgical system2000 preferably also includes a fixture configured to conveniently mountone or more components to the surgical viewing device 2004.

In one embodiment, the alignment device 2008 includes an alignmentmodule 2020, a marking module 2024, and an image capture module 2028. Asdiscussed below, in another embodiment, the marking module 2024 iseliminated. Where the marking module 2024 is eliminated, one or more ofits functions may be performed by the image capture module 2028. Inanother embodiment, the image capture module 2028 is eliminated. Thealignment device 2004 preferably also has a control device 2032 thatdirects one or more components of the alignment device 2004. Asdiscussed more fully below, the control device 2032 includes a computer2036 and signal lines 2040 a, 2040 b, and a trigger 2042 in oneembodiment.

The alignment module 2020 includes components that enable a patient toalign a feature related to the patient's eye, vision, or sense of sightwith an instrument axis, e.g., an axis of the alignment device 2008. Inone embodiment, the alignment module 2020 includes a plurality oftargets (e.g., two targets) that are located on the instrument axis. Inthe illustrated embodiment, the alignment module 2020 includes a firsttarget 2056 and a second target 2060. The alignment module 2020 may beemployed to align the patient's line-of-sight with an axis 2052 thatextends perpendicular to the faces of the targets 2056, 2060.

Although the alignment device 2008 could be configured such that thepatient is positioned relative thereto so that the eye is positionedalong the axis 2052, it may be more convenient to position the patientsuch that an eye 2064 of the patient is not on the axis 2052. Forexample, as shown in FIG. 55, the patient may be positioned a distance2068 from the axis 2052. FIG. 55 shows that the gaze of the patient'seye 2064 is directed generally along a patient viewing axis 2072.

In this arrangement, the alignment device 2008 is configured such thatthe patient viewing axis 2072 is at about a ninety degree angle withrespect to the instrument axis 2052. In this embodiment, a path 2076optically connecting the targets 2056, 2060 with the patient's eye 2064extends partially along the axis 2052 and partially along the patientviewing axis 2072. The optical path 2076 defines the path along whichthe images of the targets 2056, 2060 are cast when the alignment device2008 is configured such that the patient's eye 2064 is not on the axis2052.

Positioning the patient off of the axis 2052, may be facilitated by oneor more components that redirect light traveling along or parallel tothe axis 2052. In one embodiment, the alignment device 2008 includes abeamsplitter 2080 located on the axis 2052 to direct along the patientviewing axis 2072 light rays coming toward the beamsplitter 2080 fromthe direction of the targets 2056, 2060. In this embodiment, at least aportion of the optical path 2076 is defined from the patient's eye 2064to the beamsplitter 2080 and from the beamsplitter 2080 to the first andsecond targets 2056, 2060. Although the alignment device 2008 isconfigured to enable the patient viewing axis 2072 to be at about aninety degree angle with respect to the axis 2052, other angles arepossible and may be employed as desired. The arrangement of FIG. 55 isconvenient because it enables a surgeon to be directly above andrelatively close to the patient if the patient is positioned on his orher back on an operating table.

In one embodiment, the first target 2056 is on the axis 2052 and on theoptical path 2076 between the second target 2060 and the patient's eye2064. More particularly, light rays that are directed from the secondtarget 2060 intersect the first target 2056 and are thereafter directedtoward the beamsplitter 2080. As discussed more fully below, the firstand second targets 2056, 2060 are configured to project a suitablepattern toward the patient's eye 2064. The patient interacts with theprojected images of the first and second targets 2056, 2060 to align theline-of-sight (or other unique anatomical feature) of the patient's eye2064 or of the patient's sense of vision with an axis of the instrument,such as the axis 2052, the viewing axis 2072, or the optical path 2076.

The first and second targets 2056, 2060 may take any suitable form. Thetargets 2056, 2060 may be similar to those hereinbefore described. Thetargets 2056, 2060 may be formed on separate reticles or as part of asingle alignment target. In one embodiment, at least one of the firstand second targets 2056, 2060 includes a glass reticle with a patternformed thereon. The pattern on the first target 2056 and the pattern onthe second target 2060 may be linear patterns that are combined to forma third linear pattern when the patient's line-of-sight is aligned withthe axis 2052 or optical path 2076.

Although shown as separate elements, the first and second targets 2056,2060 may be formed on a alignment target. FIGS. 55A-55C shows oneembodiment of an alignment target 2081. The alignment target 2081 can beformed of glass or another substantially transparent medium. Thealignment target 2081 includes a first surface 2082 and a second surface2083. The first and second surfaces 2082, 2083 are separated by adistance 2084. The distance 2084 is selected to provide sufficientseparation between the first and second surfaces 2082, 2083 tofacilitate alignment by the patient by any of the methods describedherein. In one embodiment, the alignment target 2081 includes a firstpattern 2085 that may comprise a linear pattern formed on the firstsurface 2082 and a second pattern 2086 that may comprise a linearpattern formed on the second surface 2083. The first and second patterns2085, 2086 are selected so that when the patient's line-of-sight isproperly aligned with an axis of the alignment device 2008, the firstand second patterns 2085, 2086 form a selected pattern (as in FIG. 55B)but when the patient's line-of-sight is properly aligned with an axis ofthe alignment device 2008, the first and second patterns 2085, 2086 donot form the selected pattern (as in FIG. 55C). In the illustratedembodiment, the first and second pattern 2085, 2086 each are generallyL-shaped. When aligned, the first and second patterns 2085, 2086 form across. When not aligned, a gap is formed between the patterns and theyappear as an L and an inverted L. This arrangement advantageouslyexploits vernier acuity, which is the ability of the eye to keenlydetect misalignment of displaced lines. Any other combination ofnon-linear or linear patterns (e.g., other linear patterns that exploitvernier acuity) can be used as targets, as discussed above.

The first and second targets 2056, 2060 (or the first and secondpatterns 2085, 2086) may be made visible to the patient's eye 2064 inany suitable manner. For example, a target illuminator 2090 may beprovided to make the targets 2056, 2060 visible to the eye 2064. In oneembodiment, the target illuminator 2090 is a source of radiant energy,such as a light source. The light source can be any suitable lightsource, such as an incandescent light, a fluorescent light, one or morelight emitting diodes, or any other source of light to illuminate thetargets 2056, 2060.

As discussed more fully below, the alignment module 2020 also mayinclude one or more optic elements, such as lenses, that relativelysharply focus the images projected from the first and second targets2056, 2060 to present sharp images to the patient's eye 2064. In sucharrangements, the focal length of the optic element or system of opticalelements may be located at any suitable location, e.g., at the first orsecond targets 2056, 2060, between the first and second targets 2056,2060 in front of the first target 2056, or behind the second target2060. The focal length is the distance from a location (e.g., thelocation of an optic element) to the plane at which the optic elementfocuses the target images projected from the first and second target2056, 2060.

FIG. 55 shows a series of arrows that indicate the projection of theimages of the first and second targets 2056, 2060 to the patient's eye2064. In particular, an arrow 2094 indicates the direction of light castby the target illuminator 2090 along the axis 2052 toward the first andsecond targets 2056, 2060. The light strikes the first and secondtargets 2056, 2060 and is absorbed by or passed through the targets tocast an image of the targets 2056, 2060 along the axis 2052 in adirection indicated by an arrow 2098. In the embodiment of FIG. 55, theimage of the first and second targets 2056, 2060 intersects abeamsplitter 2102 that forms a part of the marking module 2024 and theimage capture module 2028. The beamsplitter 2102 is configured totransmit the majority of the light conveying the images of the first andsecond targets 2056, 2060 toward the beamsplitter 2080 as indicated byan arrow 2106. The beamsplitter 2102 will be discussed in greater detailbelow. The light is thereafter reflected by the beamsplitter 2080 alongthe patient viewing axis 2072 and toward the patient's eye 2064. Asdiscussed more fully below, in some embodiments, the beamsplitter 2080transmits some of the incident light beyond the beamsplitter 2080 alongthe axis 2050. In one embodiment, 70 percent of the light incident onthe beamsplitter 2080 is reflected toward the patient's eye 2064 and 30percent is transmitter. One skilled in the art will recognize that thebeamsplitter 2080 can be configured to transmit and reflect in anysuitable fraction.

While the target illuminator 2090 and the first and second targets 2056,2060 project the images of the targets to the patient's eye 2064, thepatient may interact with those images to align a feature of thepatient's eye 2064 with an axis of the alignment device 2008. In theembodiment illustrated by FIG. 55, the patient aligns the line-of-sightof the eye 2064 with the patient viewing axis 2072 of the alignmentdevice 2008.

Techniques for aligning the line of sight of the patient's eye 2064 withthe instrument axis have been discussed above. In the context of theembodiment of FIG. 55, the patient is positioned such that the opticalpath 2076 intersects the patient's eye 2064. In one method, the patientis instructed to focus on the first target 2056. Motion is providedbetween the patient's eye 2064 and the optical path 2076 (and thereforebetween the patient's eye 2064 and the targets 2056, 2060). The relativemotion between the patient's eye 2064 and the targets 2056, 2060 may beprovided by the patient moving his or her head with respect to thepatient viewing axis 2072. Alternatively, the patient may be enabled tomove all or a portion of the surgical system 2000 while the patientremains stationary. As discussed above, when the first and secondtargets 2056, 2060 appear aligned (e.g., the L patterns 2085, 2086 mergeto form a cross), the line-of-sight of the patient is aligned with thepatient viewing axis 2072, the optical path 2076, and the axis 2052 ofthe alignment module 2020.

Although aligning the eye may be sufficient to provide relativelyprecise placement of the masks described herein, one or both of themarking module 2024 and the image capture module 2028 may be included toassist the surgeon in placing a mask after the eye 2064 has beenaligned. At least one of the marking module 2024 and the image capturemodule 2028 may be used to correlate the line-of-sight of the patient'seye 2064, which is not otherwise visible, with a visual cue, such as avisible physical feature of the patient's eye, a marker projected ontothe eye or an image of the eye, or a virtual image of a marker visibleto the surgeon, or any combination of the foregoing. As is discussed inmore detail below, the virtual image may be an image that is directedtoward the surgeon's eye that appears from the surgeon's point of viewto be on the eye 2064 at a pre-selected location.

In one embodiment, the marking module 2024 is configured to produce animage, sometimes referred to herein as a “marking image”, that isvisible to the surgeon and that is assists the surgeon in placing a maskor performing another surgical procedure after the line of sight of theeye 2064 has been located. The marking module 2024 of the alignmentdevice 2008 shown includes a marking target 2120 and a marking targetilluminator 2124. The marking target illuminator 2124 preferably is asource of light, such as any of those discussed above in connection withthe target illuminator 2090.

FIG. 55 shows that in one embodiment, the marking target 2120 is astructure configured to produce a marking image when light is projectedonto the marking target 2120. The marking target 2120 may be similar tothe targets 2056, 2060. In some embodiments, the marking target 2120 isa glass reticle with a suitable geometrical pattern formed thereon. Thepattern formed on the marking target 2120 may be a clear two dimensionalshape that is surrounded by one or more opaque regions. For example, aclear annulus of selected width surrounded by opaque regions could beprovided. In another embodiment, the marking target 2120 may be a glassreticle with an opaque two dimensional shape surrounded by substantiallyclear regions. As discussed below, in other embodiments, the markingtarget 2120 need not be made of glass and need not have a fixed pattern.The marking target 2120 may be located in any suitable location withrespect to the beamsplitter 2080 or the alignment device 2008 asdiscussed below.

FIG. 55 shows that in one embodiment, the marking image is generated ina manner similar to the manner in which the images of the first andsecond targets 2056, 2060 are generated. In particular, the markingtarget 2124 and the marking target illuminator 2124 cooperate toproduce, generate, or project the marking image along a marking imageaxis 2128. The marking image is conveyed by light along the axis 2128.The marking target illuminator 2124 casts light toward the markingtarget 2120 in a direction indicated by an arrow 2132. The markingtarget 2120 interacts with the light cast by the marking targetilluminator 2124, e.g., by at least one of transmitting, absorbing,filtering, and attenuating at least a portion of the light. An arrow2136 indicates the direction along which the marking image generated bythe interaction of the marking target illuminator 2124 and the markingtarget 2120 is conveyed. The marking image preferably is conveyed alongthe marking axis 2128. In the illustrated embodiment, the marking target2120 is located off of the axis 2052 and the image of the marking targetinitially is cast in a direction generally perpendicular to the axis2052.

A beamsplitter 2140, to be discussed below in connection with the imagecapture module 2028, is positioned on the marking axis 2128 in theembodiment of FIG. 55. However, the beamsplitter 2140 is configured tobe substantially transparent to light being transmitted along themarking axis 2128 from the direction of the marking target 2120. Thus,the light conveying the marking image is substantially entirelytransmitted beyond the beamsplitter 2140 along the marking axis 2128toward the axis 2052 as indicated by an arrow 2144. Thus, thebeamsplitter 2140 generally does not affect the marking image. A surfaceof the beamsplitter 2102 that faces the marking target 2120 isreflective to light. Thus, the light conveying the marking image isreflected and thereafter is conveyed along the axis 2052 as indicated bythe arrow 2106. The surface of the beamsplitter 2080 that faces thebeamsplitter 2102 also is reflective to at least some light (e.g., 70percent of the incident light, as discussed above). Thus, the lightconveying the marking image is reflected and thereafter is conveyedalong the patient viewing axis 2072 toward the patient's eye 2064 asindicated by the arrow 2148. Thus, a marking image projected from themarking target 2120 may be projected onto the patient's eye 2064.

As discussed more fully below, projecting the marking image onto thepatient's eye 2064 may assist the surgeon in accurately placing a mask.For example, the surgeon may be assisted in that the location ofline-of-sight of the patient's eye (or some other generally invisiblefeature of the eye 2064) is correlated with a visible feature of theeye, such as the iris or other anatomical feature. In one technique, themarking image is a substantially circular ring that has a diameter thatis greater than the size of the inner periphery of the iris undersurgical conditions (e.g., the prevailing light and the state ofdilation of the patient's eye 2064). In another technique, the markingimage is a substantially circular ring that has a diameter that is lessthan the size of the outer periphery of the iris under surgicalconditions (e.g., light and dilation of the eye 2064). In anothertechnique, the marking image is a substantially circular ring that has asize that is correlated to another feature of the eye 2064, e.g., thelimbus of the eye.

In one embodiment of the system 2000, a marking module is provided thatincludes a secondary marking module. The secondary marking module is notrouted through the optics of associated with the alignment device 2008.Rather, the secondary marking module is coupled with the alignmentdevice 2008. In one embodiment, the secondary marking module includes asource of radiant energy, e.g., a laser or light source similar to anyof these discussed herein. The source of radiant energy is configured todirect a plurality of spots (e.g., two, three, four, or more than fourspots) onto the patient's eye 2064. The spots preferably are small,bright spots. The spots indicate positions on the eye 2064 thatcorrelate with a feature of a mask, such as an edge of a mask, when themask is in the correct position with respect to the line-of-sight of theeye 2064. The spots can be aligned with the projected marking targetsuch that they hit at a selected location on the projected markingtarget (e.g., circumferentially spaced locations on the inner edge, onthe outer edge, or on both the inner and outer edges). Thus, the markingmodule may give a visual cue as to the proper positioning of a mask thatis correlated to the location of the line-of-sight without passingthrough the optics of the alignment device. The visual cue of thesecondary marking module may be coordinated with the marking image ofthe marking module 2024 in some embodiments.

In some techniques, it may be beneficial to increase the visibility of avisual cue generated for the benefit of the surgeon (e.g., thereflection of the image of the marking target 2120) on the eye 2064. Insome cases, this is due to the generally poor reflection of markingimages off of the cornea. Where reflection of the marking image off ofthe cornea is poor, the reflection of the image may be quite dim. Inaddition, the cornea is an off-center aspherical structure, so thecorneal reflection (purkinje images) may be offset from the location ofthe intersection of the visual axis and the corneal surface as viewed bythe surgeon.

One technique for increasing the visibility of a visual cue involvesapplying a substance to the eye that can react with the projected imageof the marking target 2120. For example, a dye, such as fluorescein dye,can be applied to the surface of the eye. Then the marking targetilluminator 2124 may be activated to cause an image of the markingtarget 2120 to be projected onto the eye, as discussed above. In oneembodiment, the marking target illuminator 2124 is configured to projectlight from all or a discrete portion of the visible spectrum ofelectromagnetic radiant energy, e.g., the wavelengths corresponding toblue light, to project the image of the marking target 2120 onto the eye2064. The projected image interacts with the dye and causes the image ofthe marking target 2120 to be illuminated on the surface of the cornea.The presence of the dye greatly increases the visibility of the image ofthe marking target. For example, where the marking target 2120 is aring, a bright ring will be visible to the surgeon because the lightcauses the dye to fluoresce. This technique substantially eliminateserrors in placement of a mask due to the presence of the purkinje imagesand may generally increase the brightness of the image of the markingtarget 2120.

Another technique for increasing the visibility of a visual cue on theeye involves applying a visual cue enhancing device to at least aportion of the anterior surface of the eye 2064. For example, in onetechnique, a drape is placed over the cornea. The drape may have anysuitable configuration. For example, the drape may be a relatively thinstructure that will substantially conform to the anterior structure ofthe eye. The drape may be formed in a manner similar to the formation ofa conventional contact lens. In one technique, the drape is a contactlens. The visual cue enhancing device preferably has suitable reflectingproperties. In one embodiment, the visual cue enhancing device diffuselyreflects the light projecting the image of the marking target 2120 ontothe cornea. In one embodiment, the visual cue enhancing device isconfigured to interact with a discrete portion of the visible spectrumof electromagnetic radiant energy, e.g., the wavelengths thereofcorresponding to blue light.

As discussed above the alignment device 2008 shown in FIG. 55 alsoincludes an image capture module 2028. Some variations do not includethe image capture module 2028. The image capture module 2028 of thesurgical system 2000 is capable of capturing one or more images of thepatient's eye 2064 to assist the surgeon in performing surgicalprocedures on the eye 2064. The image capture module 2028 preferablyincludes a device to capture an image, such as a camera 2200 and adisplay device 2204 to display an image. The display device 2204 may bea liquid crystal display. The image capture module 2028 may becontrolled in part by the control device 2032 of the surgical system2000. For example, the computer 2036 may be employed to process imagescaptured by the camera 2200 and to convey an image to the display device2204 where it is made visible to the surgeon. The computer 2036 may alsodirect the operation of or be responsive to at least one of the camera2200, the display device 2204, the trigger 2042, and any other componentof the image capture module 2028.

The camera 2200 can be any suitable camera. One type of camera that canbe used is a charge-coupled device camera, referred to herein as a CCDcamera. One type of CCD camera incorporates a silicon chip, the surfaceof which includes light-sensitive pixels. When light, e.g., a photon orlight particle, hits a pixel, an electric charge is registered at thepixels that can be detected. Images of sufficient resolution can begenerated with a large array of sensitive pixels. As discussed morefully below, one advantageous embodiment provides precise alignment of aselected pixel (e.g., one in the exact geometric center of the displaydevice 2204) with the axis 2052. When such alignment is provided, themarking module may not be needed to align a mask with the line-of-sightof the eye 2064.

As discussed above, an image captured by the camera 2200 aids thesurgeon attempting to align a mask, such as any of the masks describedherein, with the eye 2064. In one arrangement, the image capture module2028 is configured to capture an image of one or more physicalattributes of the eye 2064, the location of which may be adequatelycorrelated to the line-of-sight of the eye 2064. For example, the imageof the patient's iris may be directed along the patient viewing axis2072 to the beamsplitter 2080 as indicated by the arrow 2148. Asmentioned above, a side of the beamsplitter 2080 that faces thebeamsplitter 2080 is reflective to light transmitted from the eye 2064.Thus, at least a substantial portion of the light conveying the image ofthe iris of the eye 2064 is reflected by the beamsplitter 2080 and isconveyed along the axis 2052 toward the beamsplitter 2102, as indicatedby the arrow 2106. As discussed above, the surface of the beamsplitter2102 facing the beamsplitter 2080 is reflective to light. Thus,substantially all of the light conveying the image of the iris isreflected by the beamsplitter 2102 and is conveyed along the markingaxis 2128 toward the beamsplitter 2140, as indicated by the arrow 2144.The surface of the beamsplitter 2140 facing the beamsplitter 2102 andthe camera 2200 is reflective to light. Thus, substantially all of thelight conveying the image of the iris is reflected along an imagecapture axis 2212 that extends between the beamsplitter 2140 and thecamera 2200. The light is conveyed along an image capture axis 2212 asindicated by an arrow 2216.

The image captured by the camera 2200 is conveyed to the computer 2036by way of a signal line 2040 a. The computer 2036 processes the signalin a suitable manner and generates signals to be conveyed along a signalline 2040 b to the display device 2204. Any suitable signal line andcomputer or other signal processing device can be used to convey signalsfrom the camera 2200 to the display device 2204. The signal lines 2040a, 2040 b need not be physical lines. For example, any suitable wirelesstechnology may be used in combination with or in place of physical linesor wires.

The capturing of the image by the camera 2200 may be triggered in anysuitable way. For example, the trigger 2042 may be configured to bemanually actuated. In one embodiment, the trigger 2042 is configured tobe actuated by the patient when his or her eye 2064 is aligned (e.g.,when the targets 2056, 2060 are aligned, as discussed above). Byenabling the patient to trigger the capturing of the image of the eye2064 by the image capture module 2028, the likelihood of the eye 2064moving prior to the capturing of the image is greatly reduced. Inanother embodiment, another person participating in the procedure may bepermitted to trigger the capturing of the image, e.g., on the patient'scue. In another embodiment, the control device 2032 may be configured toautomatically capture the image of the patient's eye 2064 based on apredetermined criteria.

The display device 2204 is configured to be illuminated to direct animage along the axis 2052 toward the beamsplitter 2080 as indicated byan arrow 2208. The surface of the beamsplitter 2080 that faces thedisplay device 2204 preferably is reflective to light directed from thelocation of the beamsplitter 2080. Thus, the image on the display 2052is reflected by the beamsplitter 2080 toward an eye 2212 of the surgeonas indicated by an arrow 2216. The beamsplitter 2080 preferably istransparent from the perspective of the surgeon's eye 2212. Thus, thesurgeon may simultaneously view the patient's eye 2064 and the image onthe display device 2204 in one embodiment. In one embodiment where boththe marking module 2024 and the image capture module 2028 are present,the marking image may be projected at the same time that an image isdisplayed on the display device 2204. The marking image and the image onthe display will appear to both be on the patient's eye. In onearrangement, they have the same configuration (e.g., size and shape) andtherefore overlap. This can reinforce the image from the perspective ofthe surgeon, further increasing the visibility of the visual cueprovided by the marking image.

The display device 2204 is located at a distance 2220 from thebeamsplitter 2080. The patient is located a distance 2224 from the axis2052. Preferably the distance 2220 is about equal to the distance 2224.Thus, both the display device 2204 and the patient's eye 2064 are at thefocal length of the surgical viewing device 2004. This assures that theimage generated by the display device 2204 is in focus at the same timethat the patient's eye is in focus.

In one embodiment, the system 2000 is configured to track movement ofthe patient's eye 2064 during the procedure. In one configuration, thetrigger 2042 is actuated by the patient when the eye 2064 is alignedwith an axis of the alignment device 2008. Although a mask is implantedshortly thereafter, the patient's eye is not constrained and maythereafter move to some extent. In order to correct for such movement,the image capture module 2028 may be configured to respond to suchmovements by moving the image formed on the display device 2204. Forexample, a ring may be formed on the display device 2204 that is similarto those discussed above in connection with the marking target 2120. Thebeamsplitter 2080 enables the surgeon to see the ring visually overlaidon the patient's eye 2064. The image capture module 2028 compares thereal-time position of the patient's eye 2064 with the image of the eyecaptured when the trigger 2042 is actuated. Differences in the real-timeposition and the position captured by the camera 2200 are determined.The position of the ring is moved an amount corresponding to thedifferences in position. As a result, from the perspective of thesurgeon, movements of the ring and the eye correspond and the ringcontinues to indicate the correct position to place a mask.

As discussed above, several variations of the system 2000 arecontemplated. A first variation is substantially identical to theembodiment shown in FIG. 55, except as set forth below. In the firstvariation, the video capture module 2028 is eliminated. This embodimentis similar to that set forth above in connection with FIG. 51. In thearrangement of FIG. 55, the marking module 2024 is configured to projectthe marking target onto the surface of the patient's eye. This variationis advantageous in that it has a relatively simple construction. Also,this variation projects the marking image onto the surface of thecornea, proximate the surgical location.

In one implementation of the first variation, the marking module 2024 isconfigured to display the marking image to the surgeon's eye 2212 butnot to the patient's eye 2064. This may be provided by positioning themarking target 2120 approximately in the location of the display device2204. The marking image may be generated and presented to the surgeon inany suitable manner. For example, the marking target 2120 and markingtarget illuminator 2124 may be repositioned so that they project theimage of the marking target 2120 as indicated by the arrows 2208, 2216.The marking target 2120 and the marking target illuminator 2124 may bereplaced by a unitary display, such as an LCD display. Thisimplementation of the first variation is advantageous in that themarking image is visible to the surgeon but is not visible to thepatient. The patient is freed from having to respond to or being subjectto the marking image. This can increase alignment performance byincreasing patient comfort and decreasing distractions, thereby enablingthe patient to remain still during the procedure.

In another implementation of the first variation, a dual marking imageis presented to the eye 2212 of the surgeon. In one form, thisimplementation has a marking module 2024 similar to that shown in FIG.55 and discussed above, except as set forth below. A virtual image ispresented to the surgeon's eye 2212. In one form, a virtual imagegeneration surface is positioned in substantially the same location asthe display device 2204. The surface may be a mirror, another reflectivesurface, or a non-reflective surface. In one embodiment, the displaydevice 2204 is a white card. A first fraction of the light conveying themarking image is reflected by the beamsplitter 2080 to the patient's eye2064. The marking image is thus formed on the patient's eye. A secondfraction of the light conveying the marking image is transmitted to thevirtual image generation surface. The marking image is formed on orreflected by the virtual image generation surface. The marking targetthus also is visible to the surgeon's eye 2212 in the form of a virtualimage of the target. The virtual image and the marking image formed onthe patient's eye are both visible to the surgeon. This implementationof the first variation is advantageous in that the virtual image and themarking image of the marking target are visible to the surgeon's eye2212 and are reinforced each other making the marking image highlyvisible to the surgeon.

In a second variation, the marking module 2024 is eliminated. In thisembodiment, the image capture module 2028 provides a visual cue for thesurgeon to assist in the placement of a mask. In particular, an imagecan be displayed on the display device 2204, as discussed above. Theimage can be generated in response to the patient actuating the trigger2042. In one technique, the patient actuates the trigger when thetargets 2056, 2060 appear aligned, as discussed above. In thisvariation, care should be taken to determine the position of the displaydevice 2204 in the alignment device because the image formed on thedisplay device 2204 is to give the surgeon a visual cue indicating thelocation of the line-of-sight of the patient. In one embodiment, thedisplay device 2204 is carefully coupled with the alignment module sothat the axis 2052 extends through a known portion (e.g., a known pixel)thereof. Because the precise location of the axis 2052 on the displaydevice 2204 is known, the relationship of the image formed thereon tothe line-of-sight of the patient is known.

FIG. 56 shows a portion of a surgical system 2400 that is similar to thesurgical system 2000 discussed above except as set forth below. Thesurgical system 2400 may be modified according to any of the variationsand embodiments hereinbefore described.

The portion of the surgical system 2400 is shown from the surgeon'sviewpoint in FIG. 56. The surgical system 2400 includes an alignmentdevice 2404 and a fixture 2408. The alignment device 2404 is similar tothe alignment device 2008 discussed above, except as set forth below.The surgical system 2400 is shown without a surgical microscope or otherviewing device, but is configured to be coupled with one by way of thefixture 2408.

The fixture 2408 may take any suitable form. In the illustratedembodiment, the fixture 2408 includes a clamp 2412, an elevationadjustment mechanism 2416, and suitable members to interconnect theclamp 2408 and the mechanism 2416. In the embodiment of FIG. 56, theclamp 2412 is a ring clamp that includes a first side portion 2420, asecond side portion 2424, and a clamping mechanism 2426 to actuate thefirst and second side portion 2420, 2424 with respect to each other. Thefirst side portion 2420 has a first arcuate inner surface 2428 and thesecond side portion 2424 has a second arcuate inner surface 2432 thatfaces the first arcuate inner surface 2428. The clamping mechanism 2426is coupled with each of the first and second side portions 2420, 2424 tocause the first and second arcuate inner surfaces 2428, 2432 to movetoward or away from each other. As the first and second arcuate innersurfaces 2428, 2432 move toward each other they apply a force to astructure, such as a portion of a surgical microscope, placed betweenthe first and second arcuate inner surfaces 2428, 2432. In oneembodiment, the force applied by the first and second arcuate innersurfaces 2428, 2432 is sufficient to clamp the alignment device 2404with respect to a surgical viewing aid. In one embodiment, the clamp2412 is configured to couple with any one of (or more than one of) thecurrently commercially available surgical microscopes.

The fixture 2408 preferably also is configured to suspend the alignmentdevice 2404 at an elevation below the clamp 2412. In the illustratedembodiment, a bracket 2440 is coupled with the clamp 2412, which is anL-shaped bracket in the illustrated embodiment with a portion of the Lextending downward from the clamp 2412. FIG. 56 shows the L-shapedbracket spaced laterally from the clamp 2412 by a spacer 2444. In oneembodiment, the bracket 2440 is pivotably coupled with the spacer 2444so that the alignment device 2404 can be easily rotated out of the fieldof view of the surgical microscope or viewing aid, which is visiblethrough the spaced defined between the surfaces 2428, 2432.

Preferably the fixture 2408 is also configured to enable the alignmentdevice 2404 to be positioned at a selected elevation within a range ofelevations beneath the clamp 2412. The elevation of the alignment device2404 may be easily and quickly adjusted by manipulating a suitablemechanism. For example, manual actuation may be employed by providing aknob 2460 coupled with a rack-and-pinion gear coupling 2464. Of coursethe rack-and-pinion gear coupling 2464 can be actuated by another manualdevice that is more remote, such as by a foot pedal or trigger or by anautomated device.

FIGS. 57-59 show further details of the alignment device 2404. Thealignment device 2404 is operatively coupled with an illuminator controldevice 2500 and includes an alignment module 2504, a marking module2508, and an image routing module 2512. As discussed below, theilluminator control device 2500 controls light or energy sourcesassociated with the alignment control device 2404. In some embodiments,the illuminator control device 2500 forms a part of a computer or othersignal processing device, similar to the computer 2036 discussed above.

The alignment module 2504 is similar to the alignment module 2020 exceptas set forth below. The alignment module 2504 includes a housing 2520that extends between a first end 2524 and a second end 2528. The firstend 2524 of the housing 2520 is coupled with the image routing module2512 and interacts with the image routing module 2512 in a mannerdescribed below. The housing 2520 includes a rigid body 2532 thatpreferably is hollow. An axis 2536 extends within the hollow portion ofthe housing 2520 between the first and second ends 2524, 2528. In theillustrated embodiment, the second end 2528 of the housing 2520 isenclosed by an end plate 2540.

The housing 2520 is configured to protect a variety of components thatare positioned in the hollow spaced defined therein. In one embodiment,a target illuminator 2560 is positioned inside the housing 2520 near thesecond end 2528 thereof. A power cable 2564 (or other electricalconveyance) that extends from the end plate 2540 electrically connectsthe target illuminator 2560 to a power source. The target illuminator2560 could also be triggered and powered by a wireless connection. Inone arrangement, the power source forms a portion of the illuminatorcontrol device 2500 to which the power cable 2564 is connected. Powermay be from any suitable power source, e.g., from a battery orelectrical outlet of suitable voltage.

As discussed above, the illuminator control device 2500 enables thesurgeon (or other person assisting in a procedure) to control the amountof energy supplied to the target illuminator 2560 in the alignmentmodule 2504. In one embodiment, the illuminator control device 2500 hasa brightness control so that the brightness of the target illumination2560 can be adjusted. The brightness control may be actuated in asuitable manner, such as by a brightness control knob 2568. Thebrightness control may take any other suitable form to provide manualanalog (e.g., continuous) adjustment of the amount of energy applied tothe target illuminator 2560 or to provide manual digital (e.g.,discrete) adjustment of the amount of energy applied to the targetilluminator 2560. In some embodiments, the brightness control may beadjustable automatically, e.g., under computer control. The illuminatorcontrol device 2500 may also have an on-off switch 2572 configured toselectively apply and cut off power to the target illuminator 2560. Theon-off switch 2572 may be operated manually, automatically, or in apartially manual and partially automatic mode. The brightness controland on-off switch could be controlled wirelessly in another embodiment.

Also located in the housing 2520 are a first target 2592, a secondtarget 2596, and a lens 2600. As discussed above, the first and secondtargets 2592, 2596 are configured to present a composite image to thepatient's eye such that the patient may align the line-of-sight of theeye with an axis (e.g., the axis 2536) of the alignment module 2504. Thefirst and second targets 2592, 2596 are similar to the targets discussedabove. In particular, the alignment target 2081, which includes twotargets on opposite ends of a single component, may be positioned withinthe housing 2520.

The lens 2600 may be any suitable lens. Preferably the lens 2600 isconfigured to sharply focus one or both of the images of the first andsecond targets 2592, 2596 in a manner similar to the focus of thetargets 2056, 2060, discussed above.

In one embodiment, the alignment module 2504 is configured such that theposition of the first and second targets 2592, 2596 within the housing2520 can be adjusted. The adjustability of the first and second targets2592, 2596 may be provided with any suitable arrangement. FIGS. 57-58shows that in one embodiment the alignment module 2504 includes a targetadjustment device 2612 to provide rapid gross adjustment and fineadjustment of the positions of the targets 2592, 2596 within the housing2520.

In one embodiment, the target adjustment device 2612 includes a supportmember 2616 that extends along at least a portion of the housing 2520between the first end 2524 and the second end 2528. In one embodiment,the support member 2616 is coupled with the end plate 2540 and with theimage routing module 2512. In one embodiment, the target adjustmentdevice 2612 includes a lens fixture 2620 that is coupled with the lens2600 and a target fixture 2624 that is coupled with the first and secondtargets 2592, 2596. In another embodiment, each of the first and secondtargets 2592, 2596 is coupled with a separate target fixture so that thetargets may be individually positioned and adjusted. The lens 2600 maybe adjustable as shown, or in a fixed position. Movement of the lens andthe targets 2592, 2596 enable the patterns on the targets 2592, 2596 tobe brought into focus from the patient's point of view.

In one arrangement, the support member 2616 is a threaded rod and eachof the first and second target fixtures 2620, 2624 has a correspondingthreaded through hole to receive the threaded support member 2616.Preferably an adjustment device, such as a knob 2628 is coupled with thethreaded support member 2616 so that the support member 2616 may berotated. The knob 2628 may be knurled to make it easier to grasp androtate. Rotation of the support member 2616 causes the first and secondtarget fixtures 2620, 2624 to translate on the support member 2616 alongthe outside of the housing 2520. The movement of the first and secondtarget fixtures 2620, 2624 provides a corresponding movement of thefirst and second targets 2592, 2596 within the housing 2520.

In one embodiment a quick release mechanism 2640 is provided to enablethe first and second target fixtures 2620, 2624 selectively to clamp andto release the support member 2616. The quick release mechanism 2640 canbe a spring loaded clamp that causes the through holes formed in thefirst and second target fixtures 2620, 2624 to open to create a gapthrough which the support member 2616 can pass. When the first andsecond target fixtures 2620, 2624 are removed from the support member2616, the can be quickly moved to another position on the support member2616. After rapid repositioning, fine positioning of the first andsecond target fixtures 2620, 2624 may be achieved with by turning thesupport member 2616.

As discussed above, the alignment device 2404 also includes a markingmodule 2508 that is similar to the marking module 2024 described above,except as set forth below. The marking module includes a housing 2642that is generally rigid and that defines a hollow space within thehousing. The housing 2642 includes a first end 2644 that is coupled withthe image routing module 2512 and a second end 2648 that is closed by anend plate 2652. In one embodiment, the housing 2642 includes a firstportion 2656 and a second portion 2660. The first and second portions2656, 2660 preferably are configured to be disengaged from each other sothat components located in the hollow space defined in the housing 2642to be accessed. Such rapid access facilitates servicing andreconfiguring of the components located in the housing 2642. The firstportion 2656 extends between the first end 2644 and a midpoint of thehousing 2642. The second portion 2660 extends between the first portion2656 and the second end 2648 of the housing 2642. In one embodiment, thefirst portion 2656 has a male member with external threads and thesecond portion 2660 has a female member with internal thread such thatthe first and second portions 2656, 2660 may be engaged with anddisengaged from each other by way of the threads.

As discussed above, the housing 2642 provides a space in which one ormore components may be positioned. In the illustrated embodiment, thehousing 2642 encloses a marking target illuminator 2680 and a markingtarget 2684.

The marking target illuminator 2680 may be a suitable source of radiantenergy, e.g., a light source, such as an incandescent light, afluorescent light, a light-emitting diode, or other source of radiantenergy. As with the target illuminators discussed above, the markingtarget illuminator 2680 may include or be coupled with suitable opticalcomponents to process the light generated thereby in a useful manner,e.g., by providing one or more filters to modify the light, e.g., byallowing a subset of the spectrum of light energy emitted by the lightsource (e.g., one or more bands of the electromagnetic spectrum) to betransmitted toward the marking target 2684.

In the illustrated embodiment, the marking target illuminator 2680 islocated near the end plate 2652. A power cable 2688 (or other electricalconveyance) that extends from the end plate 2652 electrically connectsthe marking target illuminator 2680 to a power source. In onearrangement, the power source forms a portion of the illuminator controldevice 2500 to which the power cable 2688 is connected. Power may befrom any suitable power source, e.g., from a battery or electricaloutlet of suitable voltage.

As discussed above, the illuminator control device 2500 enables thesurgeon (or other person assisting in a procedure) to control the amountof energy supplied to the target illuminator 2680 in the marking module2508. The illuminator control device 2500 has a brightness control sothat the brightness of the marking target illumination 2680 can beadjusted. The brightness control may be actuated in a suitable manner,such as by a brightness control knob 2692. The brightness control may besimilar to that discussed above in connection with the brightnesscontrol of the target illuminator 2560. The illuminator control device2500 may also have an on-off switch 2696 configured to selectively applyand cut off power to the marking target illuminator 2680. The on-offswitch 2696 may be operated manually, automatically, or in a partiallymanual and partially automatic mode. Any of the power supply, thebrightness control, and the on-off switch may be implemented wirelesslyin various other embodiments.

In one embodiment, the marking target 2684 is a reticle, e.g., made ofglass, with an annular shape formed thereon. For example, the annularshape formed on the marking target 2684 may be a substantially clearannulus surrounded by opaque regions. In this configuration, lightdirected toward the marking target 2684 interacts with the markingtarget 2684 to produce and annular image. In another embodiment, themarking target 2684 may be a substantially clear reticle with an opaqueshape, such as an opaque annular shape. The annular image is directedinto the image routing device 2684, as discussed further below. Themarking target 2684 may be housed in a fixture 2718 that is removable,e.g., when the first portion 2656 and the second portion 2660 of thehousing 2642 are decoupled. The first portion 2656 of the housing 2642is configured to engage the fixture 2718 to relatively preciselyposition the marking target 2684 with respect to an axis of the housing2642.

FIG. 59 shows the image routing module 2512 in greater detail. The imagerouting module 2512 is primarily useful for routing light that conveysthe target and marking images to an eye of a patient. The image routingmodule 2512 provides flexibility in the positioning of the variouscomponents of the alignment device 2404. For example, the image routingmodule 2512 enables the housing 2520 and the housing 2556 to begenerally in the same plane and positioned generally parallel to eachother. This provides a relatively compact arrangement for the alignmentdevice 2404, which is advantageous in the surgical setting because, asdiscussed above, it is desirable for the surgeon to be as close to thesurgical site as possible. In addition, the compact arrangement of thealignment device 2404 minimizes or at least reduces the extent to whichthe alignment device 2404 interferes with free movement of the surgeonand others assisting the surgeon.

FIGS. 58 and 59 shows that the image routing module 2512 includes ahousing 2720 that is coupled with the first end 2524 and the housing2520 and with the first end 2644 of the housing 2642. A space definedwithin the housing 2720 houses a first optic device 2728 and a secondoptic device 2732. The first optic device 2728 has a reflective surfacethat faces the marking target 2684 and is configured to reflect lightconveying an image of the marking target 2684 toward the second opticdevice 2732. The first optic device 2728 may be a mirror. The secondoptic device 2732 has a surface 2736 that faces the first optic device2728 and is reflective to light from the first optic device 2728. Thesecond optic device 2732 thus reflects light that is directed toward itby the first optic device 2728.

The image routing module 2512 also may include a third optic device 2740and a frame 2744 coupled with the housing 2720. The frame 2744 isconfigured to position and orient the third optic device 2740 withrespect to the housing 2720. In one embodiment, the third optic device2740 is a beamsplitter and the frame 2744 holds the third optic device2740 at about a forty-five degree angle with respect to the axis 2520.In this position, the third optic device 2740 interacts with lightreflected by the first surface 2736 of the second optic device 2732. Thethird optic device 2740 may operate in a manner similar to thebeamsplitter 2080 of FIG. 55.

The second optic device 2732 is configured to be transparent tosubstantially all of the light conveying an image along the axis 2536such that the image conveyed along the axis 2536 may be directed to thethird optic device 2740 and thereafter to an eye of a surgeon, asdiscussed about in connection with FIG. 55.

Although the image routing device is shown with first, second, and thirdoptic devices 2728, 2732, 2740 to route light conveying images in aparticular manner, one skilled in the art will recognize that the imagerouting device 2512 could have more or fewer optic devices that routethe image, depending on the desired geometry and compactness of thealignment device 2404.

A variation of the alignment device 2404 provides a marking module witha secondary marking module not routed through the optics of thealignment device 2404. In one embodiment, the secondary marking moduleincludes a source of radiant energy, e.g., a laser or other lightsource. The source of radiant energy is configured to direct a pluralityof spots (e.g., three, four, or more than four spots) onto the patient'seye. The spots indicate positions on the eye that correlate with an edgeof a mask when the mask is in the correct position with respect to theline-of-sight of the eye 2064. The spots can be aligned with theprojected marking target such that they hit at a selected location onthe projected marking target (e.g., circumferentially spaced locationson the inner edge, on the outer edge, or on both the inner and outeredges). At least a portion of the secondary marking module is coupledwith the frame 2744 in one embodiment. A laser of the secondary markingmodule could be attached to the frame 2744 and suspended therefrom,oriented downward toward the patient's eye. As discussed above, thisarrangement provides a secondary device for marking the proper locationof a mask with respect to a patient's line of sight after the line ofsight has been identified.

Although various exemplary embodiments of apparatuses and methods foraligning a patient's line-of-sight with an axis of an instrument inconnection with the application of a mask have been discussedhereinabove, it should be apparent to those skilled in the art thatvarious changes and modifications can be made which will achieve atleast some of the advantages of the invention without departing from,the true scope of the invention. These and other obvious modificationsare intended to be covered by the appended claims.

V. Masks Configured to Reduce the Visibility of Diffraction Patterns

Many of the foregoing masks can be used to improve the depth of focus ofa patient. Various additional mask embodiments are discussed below. Someof the embodiments described below include nutrient transport structuresthat are configured to enhance or maintain nutrient flow betweenadjacent tissues by facilitating transport of nutrients across the mask.The nutrient transport structures of some of the embodiments describedbelow are configured to at least substantially prevent nutrientdepletion in adjacent tissues. The nutrient transport structures candecrease negative effects due to the presence of the mask in adjacentcorneal layers when the mask is implanted in the cornea, increasing thelongevity of the masks. The inventors have discovered that certainarrangements of nutrient transport structures generate diffractionpatterns that interfere with the vision improving effect of the masksdescribed herein. Accordingly, certain masks are described herein thatinclude nutrient transport structures that do not generate diffractionpatterns or otherwise interfere with the vision enhancing effects of themask embodiments.

FIGS. 60-61 show one embodiment of a mask 3000 configured to increasedepth of focus of an eye of a patient suffering from presbyopia. Themask 3000 is similar to the masks hereinbefore described, except as setforth below. The mask 3000 is configured to be applied to an eye of apatient, e.g., by being implanted in the cornea of the patient. The mask3000 may be implanted within the cornea in any suitable manner, such asthose discussed above in connection with FIGS. 53A-54C.

In one embodiment, the mask 3000 includes a body 3004 that has ananterior surface 3008 and a posterior surface 3012. In one embodiment,the body 3004 is capable of substantially maintaining natural nutrientflow between the first corneal layer and the second corneal layer. Inone embodiment, the material is selected to maintain at least aboutninety-six percent of the natural flow of at least one nutrient (e.g.,glucose) between a first corneal layer (e.g., the layer 1410) and asecond corneal layer (e.g., the layer 1430). The body 3004 may be formedof any suitable material, including at least one of an open cell foammaterial, an expanded solid material, and a substantially opaquematerial. In one embodiment, the material used to form the body 3004 hasrelatively high water content.

In one embodiment, the mask 3000 includes and a nutrient transportstructure 3016. The nutrient transport structure 3016 may comprise aplurality of holes 3020. The holes 3020 are shown on only a portion ofthe mask 3000, but the holes 3020 preferably are located throughout thebody 3004 in one embodiment. In one embodiment, the holes 3020 arearranged in a hex pattern, which is illustrated by a plurality oflocations 3020′ in FIG. 62A. As discussed below, a plurality oflocations may be defined and later used in the later formation of aplurality of holes 3020 on the mask 3000. The mask 3000 has an outerperiphery 3024 that defines an outer edge of the body 3004. In someembodiments, the mask 3000 includes an aperture 3028 at least partiallysurrounded by the outer periphery 3024 and a non-transmissive portion3032 located between the outer periphery 3024 and the aperture 3028.

Preferably the mask 3000 is symmetrical, e.g., symmetrical about a maskaxis 3036. In one embodiment, the outer periphery 3024 of the mask 3000is circular and has a diameter of less than about 6 mm in oneembodiment. In another embodiment, the mask is circular and has adiameter in the range of 4 to 6 mm. In another embodiment, the mask 3000is circular and has a diameter of less than 4 mm. The outer periphery3024 has a diameter of about 3.8 mm in another embodiment. In someembodiments, masks that are asymmetrical or that are not symmetricalabout a mask axis provide benefits, such as enabling a mask to belocated or maintained in a selected position with respect to the anatomyof the eye.

The body 3004 of the mask 3000 may be configured to coupled with aparticular anatomical region of the eye. The body 3004 of the mask 3000may be configured to conform to the native anatomy of the region of theeye in which it is to be applied. For example, where the mask 3000 is tobe coupled with an ocular structure that has curvature, the body 3004may be provided with an amount of curvature along the mask axis 3036that corresponds to the anatomical curvature. For example, oneenvironment in which the mask 3000 may be deployed is within the corneaof the eye of a patient. The cornea has an amount of curvature thatvaries from person to person about a substantially constant mean valuewithin an identifiable group, e.g., adults. When applying the mask 3000within the cornea, at least one of the anterior and posterior surfaces3008, 3012 of the mask 3000 may be provided with an amount of curvaturecorresponding to that of the layers of the cornea between which the mask3000 is applied.

In some embodiments, the mask 3000 has a desired amount of opticalpower. Optical power may be provided by configuring the at least one ofthe anterior and posterior surfaces 3008, 3012 with curvature. In oneembodiment, the anterior and posterior surfaces 3008, 3012 are providedwith different amounts of curvature. In this embodiment, the mask 3000has varying thickness from the outer periphery 3024 to the aperture3028.

In one embodiment, one of the anterior surface 3008 and the posteriorsurface 3012 of the body 3004 is substantially planar. In one planarembodiment, very little or no uniform curvature can be measured acrossthe planar surface. In another embodiment, both of the anterior andposterior surfaces 3008, 3012 are substantially planar. In oneembodiment, the body 3004 of the mask 3000 has a thickness 3038 ofbetween about 5 micron and about 10 micron. In one embodiment, thethickness 3038 of the mask 3000 is about 5 micron. In anotherembodiment, the thickness 3038 of the mask 3000 is about 8 micron. Inanother embodiment, the thickness 3038 of the mask 3000 is about 10micron.

Thinner masks generally are more suitable for applications wherein themask 3000 is implanted at a relatively shallow location in (e.g., closeto the anterior surface of) the cornea. In thinner masks, the body 3004may be sufficiently flexible such that it can take on the curvature ofthe structures with which it is coupled without negatively affecting theoptical performance of the mask 3000. In one application, the mask 3000is configured to be implanted about 5 um beneath the anterior surface ofthe cornea. In another application, the mask 3000 is configured to beimplanted about 65 um beneath the anterior surface of the cornea. Inanother application, the mask 3000 is configured to be implanted about125 um beneath the anterior surface of the cornea. Further detailsregarding implanting the mask 3000 in the cornea are discussed above inconnection with FIGS. 53A-54C.

A substantially planar mask has several advantages over a non-planarmask. For example, a substantially planar mask can be fabricated moreeasily than one that has to be formed to a particular curvature. Inparticular, the process steps involved in inducing curvature in the mask3000 can be eliminated. Also, a substantially planar mask may be moreamenable to use on a wider distribution of the patient population (oramong different sub-groups of a broader patient population) because thesubstantially planar mask uses the curvature of each patient's cornea toinduce the appropriate amount of curvature in the body 3004.

In some embodiments, the mask 3000 is configured specifically for themanner and location of coupling with the eye. In particular, the mask3000 may be larger if applied over the eye as a contact lens or may besmaller if applied within the eye posterior of the cornea, e.g.,proximate a surface of the lens of the eye. As discussed above, thethickness 3038 of the body 3004 of the mask 3000 may be varied based onwhere the mask 3000 is implanted. For implantation at deeper levelswithin the cornea, a thicker mask may be advantageous. Thicker masks areadvantageous in some applications. For example, they are generallyeasier to handle, and therefore are easier to fabricate and to implant.Thicker masks may benefit more from having a preformed curvature thanthinner masks. A thicker mask could be configured to have little or nocurvature prior to implantation if it is configured to conform to thecurvature of the native anatomy when applied.

The aperture 3028 is configured to transmit substantially all incidentlight along the mask axis 3036. The non-transmissive portion 3032surrounds at least a portion of the aperture 3028 and substantiallyprevents transmission of incident light thereon. As discussed inconnection with the above masks, the aperture 3028 may be a through-holein the body 3004 or a substantially light transmissive (e.g.,transparent) portion thereof. The aperture 3028 of the mask 3000generally is defined within the outer periphery 3024 of the mask 3000.The aperture 3028 may take any of suitable configurations, such as thosedescribed above in connection with FIGS. 6-42.

In one embodiment, the aperture 3028 is substantially circular and issubstantially centered in the mask 3000. The size of the aperture 3028may be any size that is effective to increase the depth of focus of aneye of a patient suffering from presbyopia. For example, the aperture3028 can be circular, having a diameter of less than about 2.2 mm in oneembodiment. In another embodiment, the diameter of the aperture isbetween about 1.8 mm and about 2.2 mm. In another embodiment, theaperture 3028 is circular and has a diameter of about 1.8 mm or less.

The non-transmissive portion 3032 is configured to prevent transmissionof radiant energy through the mask 3000. For example, in one embodiment,the non-transmissive portion 3032 prevents transmission of substantiallyall of at least a portion of the spectrum of the incident radiantenergy. In one embodiment, the non-transmissive portion 3032 isconfigured to prevent transmission of substantially all visible light,e.g., radiant energy in the electromagnetic spectrum that is visible tothe human eye. The non-transmissive portion 3032 may substantiallyprevent transmission of radiant energy outside the range visible tohumans in some embodiments.

As discussed above in connection with FIG. 3, preventing transmission oflight through the non-transmissive portion 3032 decreases the amount oflight that reaches the retina and the fovea that would not converge atthe retina and fovea to form a sharp image. As discussed above inconnection with FIG. 4, the size of the aperture 3028 is such that thelight transmitted therethrough generally converges at the retina orfovea. Accordingly, a much sharper image is presented to the eye thanwould otherwise be the case without the mask 3000.

In one embodiment, the non-transmissive portion 3032 preventstransmission of about 90 percent of incident light. In anotherembodiment, the non-transmissive portion 3032 prevents transmission ofabout 92 percent of all incident light. The non-transmissive portion3032 of the mask 3000 may be configured to be opaque to prevent thetransmission of light. As used herein the term “opaque” is intended tobe a broad term meaning capable of preventing the transmission ofradiant energy, e.g., light energy, and also covers structures andarrangements that absorb or otherwise block all or less than all or atleast a substantial portion of the light. In one embodiment, at least aportion of the body 3004 is configured to be opaque to more than 99percent of the light incident thereon.

As discussed above, the non-transmissive portion 3032 may be configuredto prevent transmission of light without absorbing the incident light.For example, the mask 3000 could be made reflective or could be made tointeract with the light in a more complex manner, as discussed in U.S.Pat. No. 6,554,424, issued Apr. 29, 2003, which is hereby incorporatedby reference herein in its entirety.

As discussed above, the mask 3000 also has a nutrient transportstructure that in some embodiments comprises the plurality of holes3020. The presence of the plurality of holes 3020 (or other transportstructure) may affect the transmission of light through thenon-transmissive portion 3032 by potentially allowing more light to passthrough the mask 3000. In one embodiment, the non-transmissive portion3032 is configured to absorb about 99 percent or more of the incidentlight from passing through the mask 3000 without holes 3020 beingpresent. The presence of the plurality of holes 3020 allows more lightto pass through the non-transmissive portion 3032 such that only about92 percent of the light incident on the non-transmissive portion 3032 isprevented from passing through the non-transmissive portion 3032. Theholes 3020 may reduce the benefit of the aperture 3028 on the depth offocus of the eye by allowing more light to pass through thenon-transmissive portion to the retina.

Reduction in the depth of focus benefit of the aperture 3028 due to theholes 3020 is balanced by the nutrient transmission benefits of theholes 3020. In one embodiment, the transport structure 3016 (e.g., theholes 3020) is capable of substantially maintaining natural nutrientflow from a first corneal layer (i.e., one that is adjacent to theanterior surface 3008 of the mask 3000) to the second corneal layer(i.e., one that is adjacent to the posterior surface 3012 of the mask3000). The plurality of holes 3020 are configured to enable nutrients topass through the mask 3000 between the anterior surface 3008 and theposterior surface 3012. As discussed above, the holes 3020 of the mask3000 shown in FIG. 60 may be located anywhere on the mask 3000. Othermask embodiments described hereinbelow locate substantially all of thenutrient transport structure in one or more regions of a mask.

The holes 3020 of FIG. 60 extends at least partially between theanterior surface 3008 and the posterior surface 3012 of the mask 3000.In one embodiment, each of the holes 3020 includes a hole entrance 3060and a hole exit 3064. The hole entrance 3060 is located adjacent to theanterior surface 3008 of the mask 3000. The hole exit 3064 is locatedadjacent to the posterior surface 3012 of the mask 3000. In oneembodiment, each of the holes 3020 extends the entire distance betweenthe anterior surface 3008 and the posterior surface 3012 of the mask3000.

The transport structure 3016 is configured to maintain the transport ofone or more nutrients across the mask 3000. The transport structure 3016of the mask 3000 provides sufficient flow of one or more nutrientsacross the mask 3000 to prevent depletion of nutrients at least at oneof the first and second corneal layers (e.g., the layers 1410 and 1430).One nutrient of particular importance to the viability of the adjacentcorneal layers is glucose. The transport structure 3016 of the mask 3000provides sufficient flow of glucose across the mask 3000 between thefirst and second corneal layers to prevent glucose depletion that wouldharm the adjacent corneal tissue. Thus, the mask 3000 is capable ofsubstantially maintaining nutrient flow (e.g., glucose flow) betweenadjacent corneal layers. In one embodiment, the nutrient transportstructure 3016 is configured to prevent depletion of more than about 4percent of glucose (or other biological substance) in adjacent tissue ofat least one of the first corneal layer and the second corneal layer.

The holes 3020 may be configured to maintain the transport of nutrientsacross the mask 3000. In one embodiment, the holes 3020 are formed witha diameter of about 0.015 mm or more. In another embodiment, the holeshave a diameter of about 0.020 mm. In another embodiment, the holes havea diameter of about 0.025 mm. In another embodiment, the holes 3020 havea diameter in the range of about 0.020 mm to about 0.029 mm. The numberof holes in the plurality of holes 3020 is selected such that the sum ofthe surface areas of the hole entrances 3060 of all the holes 3000comprises about 5 percent or more of surface area of the anteriorsurface 3008 of the mask 3000. In another embodiment, the number ofholes 3020 is selected such that the sum of the surface areas of thehole exits 3064 of all the holes 3020 comprises about 5 percent or moreof surface area of the posterior surface 3012 of the mask 3000. Inanother embodiment, the number of holes 3020 is selected such that thesum of the surface areas of the hole exits 3064 of all the holes 3020comprises about 5 percent or more of surface area of the posteriorsurface 3012 of the mask 3012 and the sum of the surface areas of thehole entrances 3060 of all the holes 3020 comprises about 5 percent ormore of surface area of the anterior surface 3008 of the mask 3000.

Each of the holes 3020 may have a relatively constant cross-sectionalarea. In one embodiment, the cross-sectional shape of each of the holes3020 is substantially circular. Each of the holes 3020 may comprise acylinder extending between the anterior surface 3008 and the posteriorsurface 3012.

The relative position of the holes 3020 is of interest in someembodiments. As discussed above, the holes 3020 of the mask 3000 arehex-packed, e.g., arranged in a hex pattern. In particular, in thisembodiment, each of the holes 3020 is separated from the adjacent holes3020 by a substantially constant distance, sometimes referred to hereinas a hole pitch 3072. In one embodiment, the hole pitch 3072 is about0.062 mm.

The embodiment of FIG. 60 advantageously enables nutrients to flow fromthe first corneal layer to the second corneal layer. The inventors havediscovered that negative visual effects can arise due to the presence ofthe transport structure 3016. For example, in some cases, a hex packedarrangement of the holes 3020 can generate diffraction patterns visibleto the patient. For example, patients might observe a plurality ofspots, e.g., six spots, surrounding a central light with holes 3020having a hex patterned.

The inventors have discovered a variety of techniques that produceadvantageous arrangements of a transport structure such that diffractionpatterns and other deleterious visual effects do not substantiallyinhibit other visual benefits of a mask. In one embodiment, wherediffraction effects would be observable, the nutrient transportstructure is arranged to spread the diffracted light out uniformlyacross the image to eliminate observable spots. In another embodiment,the nutrient transport structure employs a pattern that substantiallyeliminates diffraction patterns or pushes the patterns to the peripheryof the image.

FIG. 62B-62C show two embodiments of patterns of holes 4020 that may beapplied to a mask that is otherwise substantially similar to the mask3000. The holes 4020 of the hole patterns of FIGS. 62A-62B are spacedfrom each other by a random hole spacing or hole pitch. In otherembodiments discussed below, holes are spaced from each other by anon-uniform amount, e.g., not a random amount. In one embodiment, theholes 4020 have a substantially uniform shape (cylindrical shafts havinga substantially constant cross-sectional area). FIG. 62C illustrates aplurality of holes 4020 separated by a random spacing, wherein thedensity of the holes is greater than that of FIG. 62B. Generally, thehigher the percentage of the mask body that has holes the more the maskwill transport nutrients in a manner similar to the native tissue. Oneway to provide a higher percentage of hole area is to increase thedensity of the holes. Increase hole density can also permit smallerholes to achieve the same nutrient transport as is achieved by lessdense, larger holes.

FIG. 63A shows a portion of another mask 4000 a that is substantiallysimilar to the mask 3000, except as set forth below. The mask 4000 a hasa plurality of holes 4020 a. A substantial number of the holes 4020 ahave a non-uniform size. The holes 4020 a may be uniform incross-sectional shape. The cross-sectional shape of the holes 4020 a issubstantially circular in one embodiment. The holes 4020 a may becircular in shape and have the same diameter from a hole entrance to ahole exit, but are otherwise non-uniform in at least one aspect, e.g.,in size. It may be preferable to vary the size of a substantial numberof the holes by a random amount. In another embodiment, the holes 4020 aare non-uniform (e.g., random) in size and are separated by anon-uniform (e.g., a random) spacing.

FIG. 63B illustrates another embodiment of a mask 4000 b that issubstantially similar to the mask 3000, except as set forth below. Themask 4000 b includes a body 4004 b. The mask 4000 b has a transportstructure 4016 b that includes a plurality of holes 4020 b with anon-uniform facet orientation. In particular, each of the holes 4020 bhas a hole entrance 4060 b that may be located at an anterior surface4008 b of the mask 4000 b. A facet 4062 b of the hole entrance 4060 b isdefined by a portion of the body 4004 b of the mask 4000 b surroundingthe hole entrance 4060 b. The facet 4062 b is the shape of the holeentrance 4060 b at the anterior surface 4008 b. In one embodiment, mostor all the facets 4062 b have an elongate shape, e.g., an oblong shape,with a long axis and a short axis that is perpendicular to the longaxis. The facets 4062 b may be substantially uniform in shape. In oneembodiment, the orientation of facets 4062 b is not uniform. Forexample, a substantial number of the facets 4062 may have a non-uniformorientation. In one arrangement, a substantial number of the facets 4062have a random orientation. In some embodiments, the facets 4062 b arenon-uniform (e.g., random) in shape and are non-uniform (e.g., random)in orientation.

Other embodiments may be provided that vary at least one aspect,including one or more of the foregoing aspects, of a plurality of holesto reduce the tendency of the holes to produce visible diffractionpatterns or patterns that otherwise reduce the vision improvement thatmay be provided by a mask with an aperture, such as any of thosedescribed above. For example, in one embodiment, the hole size, shape,and orientation of at least a substantial number of the holes may bevaried randomly or may be otherwise non-uniform.

FIG. 64 shows another embodiment of a mask 4200 that is substantiallysimilar to any of the masks hereinbefore described, except as set forthbelow. The mask 4200 includes a body 4204. The body 4204 has an outerperipheral region 4205, an inner peripheral region 4206, and a holeregion 4207. The hole region 4207 is located between the outerperipheral region 4205 and the outer peripheral region 4206. The body4204 may also include an aperture region, where the aperture (discussedbelow) is not a through hole. The mask 4200 also includes a nutrienttransport structure 4216. In one embodiment, the nutrient transportstructure includes a plurality of holes 4220. At least a substantialportion of the holes 4220 (e.g., all of the holes) are located in thehole region 4207. As above, only a portion of the nutrient structure4216 is shown for simplicity. But it should be understood that the hole4220 may be located through the hole region 4207.

The outer peripheral region 4205 may extend from an outer periphery 4224of the mask 4200 to a selected outer circumference 4226 of the mask4200. The selected outer circumference 4225 of the mask 4200 is locateda selected radial distance from the outer periphery 4224 of the mask4200. In one embodiment, the selected outer circumference 4225 of themask 4200 is located about 0.05 mm from the outer periphery 4224 of themask 4200.

The inner peripheral region 4206 may extend from an inner location,e.g., an inner periphery 4226 adjacent an aperture 4228 of the mask 4200to a selected inner circumference 4227 of the mask 4200. The selectedinner circumference 4227 of the mask 4200 is located a selected radialdistance from the inner periphery 4226 of the mask 4200. In oneembodiment, the selected inner circumference 4227 of the mask 4200 islocated about 0.05 mm from the inner periphery 4226.

The mask 4200 may be the product of a process that involves randomselection of a plurality of locations and formation of holes on the mask4200 corresponding to the locations. As discussed further below, themethod can also involve determining whether the selected locationssatisfy one or more criteria. For example, one criterion prohibits all,at least a majority, or at least a substantial portion of the holes frombeing formed at locations that correspond to the inner or outerperipheral regions 4205, 4206. Another criterion prohibits all, at leasta majority, or at least a substantial portion of the holes 4220 frombeing formed too close to each other. For example, such a criterioncould be used to assure that a wall thickness, e.g., the shortestdistance between adjacent holes, is not less than a predeterminedamount. In one embodiment, the wall thickness is prevented from beingless than about 20 microns.

In a variation of the embodiment of FIG. 64, the outer peripheral region4205 is eliminated and the hole region 4207 extends from the innerperipheral region 4206 to an outer periphery 4224. In another variationof the embodiment of FIG. 64, the inner peripheral region 4206 iseliminated and the hole region 4207 extends from the outer peripheralregion 4205 to an inner periphery 4226.

FIG. 61B shows a mask 4300 that is similar to the mask 3000 except asset forth below. The mask 4300 includes a body 4304 that has an anteriorsurface 4308 and a posterior surface 4312. The mask 4300 also includes anutrient transport structure 4316 that, in one embodiment, includes aplurality of holes 4320. The holes 4320 are formed in the body 4304 sothat nutrient transport is provided but transmission of radiant energy(e.g., light) to the retinal locations adjacent the fovea through theholes 4304 is substantially prevented. In particular, the holes 4304 areformed such that when the eye with which the mask 4300 is coupled isdirected at an object to be viewed, light conveying the image of thatobject that enters the holes 4320 cannot exit the holes along a pathending near the fovea.

In one embodiment, each of the holes 4320 has a hole entrance 4360 and ahole exit 4364. Each of the holes 4320 extends along a transport axis4366. The transport axis 4366 is formed to substantially preventpropagation of light from the anterior surface 4308 to the posteriorsurface 4312 through the holes 4320. In one embodiment, at least asubstantial number of the holes 4320 have a size to the transport axis4366 that is less than a thickness of the mask 4300. In anotherembodiment, at least a substantial number of the holes 4320 have alongest dimension of a perimeter at least at one of the anterior orposterior surfaces 4308, 4312 (e.g., a facet) that is less than athickness of the mask 4300. In some embodiments, the transport axis 4366is formed at an angle with respect to a mask axis 4336 thatsubstantially prevents propagation of light from the anterior surface4308 to the posterior surface 4312 through the hole 4320. In anotherembodiment, the transport axis 4366 of one or more holes 4320 is formedat an angle with respect to the mask axis 4336 that is large enough toprevent the projection of most of the hole entrance 4360 fromoverlapping the hole exit 4364.

In one embodiment, the hole 4320 is circular in cross-section and has adiameter between about 0.5 micron and about 8 micron and the transportaxis 4366 is between 5 and 85 degrees. The length of each of the holes4320 (e.g., the distance between the anterior surface 4308 and theposterior surface 4312) is between about 8 and about 92 micron. Inanother embodiment, the diameter of the holes 4320 is about 5 micron andthe transport angle is about 40 degrees or more. As the length of theholes 4320 increases it may be desirable to include additional holes4320. In some cases, additional holes 4320 counteract the tendency oflonger holes to reduce the amount of nutrient flow through the mask4300.

FIG. 61C shows another embodiment of a mask 4400 similar to the mask3000, except as set forth below. The mask 4400 includes a body 4404 thathas an anterior surface 4408, a first mask layer 4410 adjacent theanterior surface 44008, a posterior surface 4412, a second mask layer4414 adjacent the posterior surface 4412, and a third layer 4415 locatedbetween the first mask layer 4410 and the second mask layer 4414. Themask 4400 also includes a nutrient transport structure 4416 that, in oneembodiment, includes a plurality of holes 4420. The holes 4420 areformed in the body 4404 so that nutrient are transported across themask, as discussed above, but transmission of radiant energy (e.g.,light) to retinal locations adjacent the fovea through the holes 4404 issubstantially prevented. In particular, the holes 4404 are formed suchthat when the eye with which the mask 4400 is coupled is directed at anobject to be viewed, light conveying the image of that object thatenters the holes 4420 cannot exit the holes along a path ending near thefovea.

In one embodiment, at least one of the holes 4420 extends along anon-linear path that substantially prevents propagation of light fromthe anterior surface to the posterior surface through the at least onehole. In one embodiment, the mask 4400 includes a first hole portion4420 a that extends along a first transport axis 4466 a, the second masklayer 4414 includes a second hole portion 4420 b extending along asecond transport axis 4466 b, and the third mask layer 4415 includes athird hole portion 4420 c extending along a third transport axis 4466 c.The first, second, and third transport axes 4466 a, 4466 b, 4466 cpreferably are not collinear. In one embodiment, the first and secondtransport axes 4466 a, 4466 b are parallel but are off-set by a firstselected amount. In one embodiment, the second and third transport axes4466 b, 4466 c are parallel but are off-set by a second selected amount.In the illustrated embodiment, each of the transport axes 44466 a, 4466b, 4466 c are off-set by one-half of the width of the hole portions 4420a, 4420 b, 4420 c. Thus, the inner-most edge of the hole portion 4420 ais spaced from the axis 4336 by a distance that is equal to or greaterthan the distance of the outer-most edge of the hole portion 4420 b fromthe axis 4336. This spacing substantially prevents light from passingthrough the holes 4420 from the anterior surface 4408 to the posteriorsurface 4412.

In one embodiment, the first and second amounts are selected tosubstantially prevent the transmission of light therethrough. The firstand second amounts of off-set may be achieved in any suitable fashion.One technique for forming the hole portions 4420 a, 4420 b, 4420 c withthe desired off-set is to provide a layered structure. As discussedabove, the mask 4400 may include the first layer 4410, the second layer4414, and the third layer 4415. FIG. 61C shows that the mask 4400 can beformed with three layers. In another embodiment, the mask 4400 is formedof more than three layers. Providing more layers may advantageouslyfurther decrease the tendency of light to be transmitted through theholes 4420 onto the retina. This has the benefit of reducing thelikelihood that a patient will observe or otherwise perceive a patterthat will detract from the vision benefits of the mask 4400. A furtherbenefit is that less light will pass through the mask 4400, therebyenhancing the depth of focus increase due to the pin-hole sized apertureformed therein.

In any of the foregoing mask embodiments, the body of the mask may beformed of a material selected to provide adequate nutrient transport andto substantially prevent negative optic effects, such as diffraction, asdiscussed above. In various embodiments, the masks are formed of an opencell foam material. In another embodiment, the masks are formed of anexpanded solid material.

As discussed above in connection with FIGS. 62B and 62C, various randompatterns of holes may advantageously be provided for nutrient transport.In some embodiment, it may be sufficient to provide regular patternsthat are non-uniform in some aspect. Non-uniform aspects to the holesmay be provided by any suitable technique.

In a first step of one technique, a plurality of locations 4020′ isgenerated. The locations 4020′ are a series of coordinates that maycomprise a non-uniform pattern or a regular pattern. The locations 4020′may be randomly generated or may be related by a mathematicalrelationship (e.g., separated by a fixed spacing or by an amount thatcan be mathematically defined). In one embodiment, the locations areselected to be separated by a constant pitch or spacing and may be hexpacked.

In a second step, a subset of the locations among the plurality oflocations 4020′ is modified to maintain a performance characteristic ofthe mask. The performance characteristic may be any performancecharacteristic of the mask. For example, the performance characteristicmay relate to the structural integrity of the mask. Where the pluralityof locations 4020′ is selected at random, the process of modifying thesubset of locations may make the resulting pattern of holes in the maska “pseudo-random” pattern.

Where a hex packed pattern of locations (such as the locations 3020′ ofFIG. 62A) is selected in the first step, the subset of locations may bemoved with respect to their initial positions as selected in the firststep. In one embodiment, each of the locations in the subset oflocations is moved by an amount equal to a fraction of the hole spacing.For example, each of the locations in the subset of locations may bemoved by an amount equal to one-quarter of the hole spacing. Where thesubset of locations is moved by a constant amount, the locations thatare moved preferably are randomly or pseudo-randomly selected. Inanother embodiment, the subset of location is moved by a random or apseudo-random amount.

In one technique, an outer peripheral region is defined that extendsbetween the outer periphery of the mask and a selected radial distanceof about 0.05 mm from the outer periphery. In another embodiment, aninner peripheral region is defined that extends between an aperture ofthe mask and a selected radial distance of about 0.05 mm from theaperture. In another embodiment, an outer peripheral region is definedthat extends between the outer periphery of the mask and a selectedradial distance and an inner peripheral region is defined that extendsbetween the aperture of the mask and a selected radial distance from theaperture. In one technique, the subset of location is modified byexcluding those locations that would correspond to holes formed in theinner peripheral region or the outer peripheral region. By excludinglocations in at least one of the outer peripheral region and the innerperipheral region, the strength of the mask in these regions isincreased. Several benefits are provided by stronger inner and outerperipheral regions. For example, the mask may be easier to handle duringmanufacturing or when being applied to a patient without causing damageto the mask.

In another embodiment, the subset of locations is modified by comparingthe separation of the holes with minimum and or maximum limits. Forexample, it may be desirable to assure that no two locations are closerthan a minimum value. In some embodiments this is important to assurethat the wall thickness, which corresponds to the separation betweenadjacent holes, is no less than a minimum amount. As discussed above,the minimum value of separation is about 20 microns in one embodiment,thereby providing a wall thickness of no less than about 20 microns.

In another embodiment, the subset of locations is modified and/or thepattern of location is augmented to maintain an optical characteristicof the mask. For example, the optical characteristic may be opacity andthe subset of locations may be modified to maintain the opacity of anon-transmissive portion of a mask. In another embodiment, the subset oflocations may be modified by equalizing the density of holes in a firstregion of the body compared with the density of holes in a second regionof the body. For example, the locations corresponding to the first andsecond regions of the non-transmissive portion of the mask may beidentified. In one embodiment, the first region and the second regionare arcuate regions (e.g., wedges) of substantially equal area. A firstareal density of locations (e.g., locations per square inch) iscalculated for the locations corresponding to the first region and asecond areal density of locations is calculated for the locationscorresponding to the second region. In one embodiment, at least onelocation is added to either the first or the second region based on thecomparison of the first and second areal densities. In anotherembodiment, at least one location is removed based on the comparison ofthe first and second areal densities.

The subset of locations may be modified to maintain nutrient transportof the mask. In one embodiment, the subset of location is modified tomaintain glucose transport.

In a third step, a hole is formed in a body of a mask at locationscorresponding to the pattern of locations as modified, augmented, ormodified and augmented. The holes are configured to substantiallymaintain natural nutrient flow from the first layer to the second layerwithout producing visible diffraction patterns.

VI. Further Methods of Treating a Patient

As discussed above in, various techniques are particularly suited fortreating a patient by applying masks such as those disclosed herein toan eye. For example, in some embodiments, the surgical system 2000 ofFIG. 55 employs a marking module 2024 that provides a visual cue in theform of a projected image for a surgeon during a procedure for applyinga mask. In addition, some techniques for treating a patient involvepositioning an implant with the aid of a marked reference point. Thesemethods are illustrated by FIGS. 65-66B.

In one method, a patient is treated by placing an implant 5000 in acornea 5004. A corneal flap 5008 is lifted to expose a surface in thecornea 5004 (e.g., an intracorneal surface). Any suitable tool ortechnique may be used to lift the corneal flap 5008 to expose a surfacein the cornea 5004. For example, a blade (e.g., a microkeratome), alaser or an electrosurgical tool could be used to form a corneal flap. Areference point 5012 on the cornea 5004 is identified. The referencepoint 5012 thereafter is marked in one technique, as discussed furtherbelow. The implant 5000 is positioned on the intracorneal surface. Inone embodiment, the flap 5008 is then closed to cover at least a portionof the implant 5000.

The surface of the cornea that is exposed is a stromal surface in onetechnique. The stromal surface may be on the corneal flap 5008 or on anexposed surface from which the corneal flap 5008 is removed.

The reference point 5012 may be identified in any suitable manner. Forexample, the alignment devices and methods described above may be usedto identify the reference point 5012. In one technique, identifying thereference point 5012 involves illuminating a light spot (e.g., a spot oflight formed by all or a discrete portion of radiant energycorresponding to visible light, e.g., red light). As discussed above,the identifying of a reference point may further include placing liquid(e.g., a fluorescein dye or other dye) on the intracorneal surface.Preferably, identifying the reference point 5012 involves alignmentusing any of the techniques described herein.

As discussed above, various techniques may be used to mark an identifiedreference point. In one technique the reference point is marked byapplying a dye to the cornea or otherwise spreading a material withknown reflective properties onto the cornea. As discussed above, the dyemay be a substance that interacts with radiant energy to increase thevisibility of a marking target or other visual cue. The reference pointmay be marked by a dye with any suitable tool. The tool is configured sothat it bites into a corneal layer, e.g., an anterior layer of theepithelium, and delivers a thin ink line into the corneal layer in oneembodiment. The tool may be made sharp to bite into the epithelium. Inone application, the tool is configured to deliver the dye as discussedabove upon being lightly pressed against the eye. This arrangement isadvantageous in that it does not form a larger impression in the eye. Inanother technique, the reference point may be marked by making animpression (e.g., a physical depression) on a surface of the cornea withor without additional delivery of a dye. In another technique, thereference point may be marked by illuminating a light or other source ofradiant energy, e.g., a marking target illuminator and projecting thatlight onto the cornea (e.g., by projecting a marking target).

Any of the foregoing techniques for marking a reference point may becombined with techniques that make a mark that indicates the location ofan axis of the eye, e.g., the visual axis or line-of-sight of the eye.In one technique, a mark indicates the approximate intersection of thevisual axis and a surface of the cornea. In another technique, a mark ismade approximately radially symmetrically disposed about theintersection of the visual axis and a surface of the cornea.

As discussed above, some techniques involve making a mark on anintracorneal surface. The mark may be made by any suitable technique. Inone technique a mark is made by pressing an implement against theinstracorneal surface. The implement may form a depression that has asize and shape that facilitate placement of a mask. For example, in oneform the implement is configured to form a circular ring (e.g., a thinline of dye, or a physical depression, or both) with a diameter that isslightly larger than the outer diameter of a mask to be implanted. Thecircular ring can be formed to have a diameter between about 4 mm andabout 5 mm. The intracorneal surface is on the corneal flap 5008 in onetechnique. In another technique, the intracorneal surface is on anexposed surface of the cornea from which the flap was removed. Thisexposed surface is sometimes referred to as a tissue bed.

In another technique, the corneal flap 5008 is lifted and thereafter islaid on an adjacent surface 5016 of the cornea 5004. In anothertechnique, the corneal flap 5008 is laid on a removable support 5020,such as a sponge. In one technique, the removable support has a surface5024 that is configured to maintain the native curvature of the cornealflap 5008.

FIG. 65 shows that the marked reference point 5012 is helpful inpositioning an implant on an intracorneal surface. In particular, themarked reference point 5012 enables the implant to be positioned withrespect to the visual axis of the eye. In the illustrated embodiment,the implant 5000 is positioned so that a centerline of the implant,indicated as M_(CL), extends through the marked reference point 5012.

FIG. 65A illustrates another technique wherein a reference 5012′ is aring or other two dimensional mark. In such a case, the implant 5000 maybe placed so that an outer edge of the implant and the ring correspond,e.g., such that the ring and the implant 5000 share the same orsubstantially the same center. Preferably, the ring and the implant 5000are aligned so that the centerline of the implant M_(CL) is on the lineof sight of the eye, as discussed above. The ring is shown in dashedlines because in the illustrated technique, it is formed on the anteriorsurface of the corneal flap 5008.

In one technique, the corneal flap 5008 is closed by returning thecorneal flap 5008 to the cornea 5004 with the implant 5000 on thecorneal flap 5008. In another technique, the corneal flap 5008 is closedby returning the corneal flap 5008 to the cornea 5004 over the implant5000, which previously was placed on the tissue bed (the exposedintracorneal surface).

When the intracorneal surface is a stromal surface, the implant 5000 isplaced on the stromal surface. At least a portion of the implant 5000 iscovered. In some techniques, the implant 5000 is covered by returning aflap with the implant 5000 thereon to the cornea 5004 to cover thestromal surface. In one technique, the stromal surface is exposed bylifting an epithelial layer to expose stroma. In another technique, thestromal surface is exposed by removing an epithelial layer to exposestroma. In some techniques, an additional step of replacing theepithelial layer to at least partially cover the implant 5000 isperformed.

After the flap 5008 is closed to cover at least a portion of the implant5000, the implant 5000 may be repositioned to some extent in someapplications. In one technique, pressure is applied to the implant 5000to move the implant into alignment with the reference point 5012. Thepressure may be applied to the anterior surface of the cornea 5004proximate an edge of the implant 5000 (e.g., directly above, above andoutside a projection of the outer periphery of the implant 5000, orabove and inside a projection of the outer periphery of the implant5000). This may cause the implant to move slightly away from the edgeproximate which pressure is applied. In another technique, pressure isapplied directly to the implant. The implant 5000 may be repositioned inthis manner if the reference point 5012 was marked on the flap 5008 orif the reference point 5012 was marked on the tissue bed.

FIG. 66 shows that a patient may also be treated by a method thatpositions an implant 5100 in a cornea 5104, e.g., in a corneal pocket5108. Any suitable tool or technique may be used to create or form thecorneal pocket 5108. For example, a blade (e.g., a microkeratome), alaser, or an electrosurgical tool could be used to create or form apocket in the cornea 5104. A reference point 5112 is identified on thecornea 5104. The reference point may be identified by any suitabletechnique, such as those discussed herein. The reference point 5112 ismarked by any suitable technique, such as those discussed herein. Thecorneal pocket 5108 is created to expose an intracorneal surface 5116.The corneal pocket 5108 may be created at any suitable depth, forexample at a depth within a range of from about 50 microns to about 300microns from the anterior surface of the cornea 5104. The implant 5100is positioned on the intracorneal surface 5116. The marked referencepoint 5112 is helpful in positioning the implant 5100 on theintracorneal surface 5116. The marked reference point 5112 enables theimplant 5100 to be positioned with respect to the visual axis of theeye, as discussed above. In the illustrated embodiment, the implant 5100is positioned so that a centerline M_(CL) of the implant 5100 extendsthrough or adjacent to the marked reference point 5112.

FIG. 66A illustrates another technique wherein a reference 5112′ is aring or other two dimensional mark. In such case, the implant 5100 maybe placed so that an outer edge of the implant and the ring correspond,e.g., such that the ring and the implant 5100 share the same orsubstantially the same center. Preferably, the ring and the implant 5100are aligned so that the centerline of the implant M_(CL) is on the lineof sight of the eye, as discussed above. The ring is shown in solidlines because in the illustrated embodiment, it is formed on theanterior surface of the cornea 5104 above the pocket 5108.

After the implant 5100 is positioned in the pocket 5108, the implant5100 may be repositioned to some extent in some applications. In onetechnique, pressure is applied to the implant 5100 to move the implantinto alignment with the reference point 5112. The pressure may beapplied to the anterior surface of the cornea 5104 proximate an edge ofthe implant 5100 (e.g., directly above, above and outside a projectionof the outer periphery of the implant 5100, or above and inside aprojection of the outer periphery of the implant 5100). This may causethe implant 5100 to move slightly away from the edge at which pressureis applied. In another technique, pressure is applied directly to theimplant 5100.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. In addition, while a number of variations of the invention havebeen shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the invention. Accordingly, it should be understood thatvarious features and aspects of the disclosed embodiments can be combinewith or substituted for one another in order to form varying modes ofthe disclosed invention. Thus, it is intended that the scope of thepresent invention herein disclosed should not be limited by theparticular disclosed embodiments described above, but should bedetermined only by a fair reading of the claims that follow.

1. A mask configured to be implanted in a cornea of a patient toincrease the depth of focus of the patient, the mask comprising: ananterior surface configured to reside adjacent a first corneal layer; aposterior surface configured to reside adjacent a second corneal layer;an aperture configured to transmit along an optical axis substantiallyall incident light and a substantially opaque portion surrounding atleast a portion of the aperture; a plurality of randomly locatednutrient flow paths in the opaque portion, the randomly located nutrientflow paths configured to permit nutrient flow between the first corneallayer and the second corneal layer; and at least one non-randomly formednutrient flow path in the opaque portion at a location that maintains atleast one performance characteristic of the mask.
 2. The mask of claim1, wherein the non-randomly formed nutrient flow path is formed at alocation that maintains the structural integrity of the mask.
 3. Themask of claim 2, wherein the non-randomly formed nutrient flow path isformed more than about 20 microns from adjacent nutrient flow paths. 4.The mask of claim 1, wherein the non-randomly formed nutrient flow pathis formed at a location that maintains optical performance of the mask.5. The mask of claim 4, wherein the non-randomly formed nutrient flowpath is formed at a location that reduces a difference in the opacitybetween a first region of the opaque portion and a second region of theopaque portion.
 6. The mask of claim 1, wherein the opaque portioncomprises a region that is substantially free of nutrient flow paths. 7.The mask of claim 6, wherein the substantially nutrient flow path freeregion is adjacent an inner periphery of the mask.
 8. The mask of claim6, wherein the substantially nutrient flow path free region is adjacentan outer periphery of the mask.
 9. The mask of claim 6, wherein thesubstantially nutrient flow path free region is between adjacentnutrient flow paths, whereby the minimum distance between adjacent flowpaths is above a minimum threshold.
 10. A mask configured to beimplanted in a cornea of a patient to increase the depth of focus of thepatient, the mask comprising: an anterior surface configured to resideadjacent a first corneal layer; a posterior surface configured to resideadjacent a second corneal layer; and an aperture configured to transmitalong an optical axis substantially all incident light and asubstantially opaque portion surrounding at least a portion of theaperture; a first plurality of nutrient flow paths being locatednon-uniformly in the opaque portion, the non-uniformly located nutrientflow paths configured to enhance nutrient flow between the first layerand the second layer; and a region within the opaque portion in whichnutrient flow paths are excluded, said region configured to maintain atleast one performance characteristic of the mask.
 11. The mask of claim10, wherein said region comprises an outer peripheral region.
 12. Themask of claim 11, wherein the outer peripheral region extends from anouter periphery of the mask to a selected outer circumference of themask, the selected outer circumference being a radial distance of about0.05 mm from the outer periphery.
 13. The mask of claim 11, furthercomprising an inner peripheral region, the nutrient flow paths beinglocated between the inner peripheral region and the outer peripheralregion.
 14. The mask of claim 13, wherein the inner peripheral regionextends from an inner periphery of the mask to a selected innercircumference of the mask, the selected inner circumference being aradial distance of about 0.05 mm from the inner periphery.
 15. The maskof claim 10, wherein said region comprises an inner peripheral region.16. The mask of claim 15, wherein the inner peripheral region extendsfrom an inner periphery of the mask to a selected inner circumference ofthe mask, the selected inner circumference being a radial distance ofabout 0.05 mm from the inner periphery.
 17. The mask of claim 10,wherein a wall thickness is defined as the shortest distance betweenadjacent nutrient flow paths, the wall thickness being no less thanabout 20 microns.
 18. The mask of claim 10, wherein said region isformed between adjacent nutrient flow paths, said region having adimension of at least about 20 microns.